Starting in 2012, the Pirates have been in contention every year, The Collapsening notwithstanding. That's been reflected in the bullpen, which finished 11th, 3rd, 9th and 1st in ERA starting with that season. A lot of the experimenting shifted to AAA, as the costs of failed major league experiments are too high for a contender. The bullpens have been much more stable. In 2012, the Pirates had five relievers appear in 60+ games. In 2013, six appeared in 50+, two of them in 67 and 72. In 2014, three appeared in 70+ and another in 63. In 2015, four appeared in 70+ and another in 66, and the team still leaned heavily on two deadline pickups in the last two months.
The nature of the team's deadline pickups also changed. Instead of trading away veteran relievers for long-term lottery tickets, they started acquiring veterans strictly for the stretch run. It's reached the point where the front office seems to assume that it will adjust the bullpen in late July, or even later. More on this in the discussion of 2015.
Joel Hanrahan (63 G, 2.72 ERA, 36 Sv): Hanrahan still put up impressive numbers, but he was showing signs of wear. His velocity dropped by a little over one mph and his xFIP, surprisingly, was 4.28. After the season, the Pirates sent him to Boston in a trade that was condemned in certain, reactionary circles as a straight salary dump.
Jason Grilli (64 G, 2.91 ERA, 2 Sv): Grilli served as the setup man and put up a crazy 13.8 K/9.
Tony Watson* (68 G, 3.38 ERA): Watson took over a regular role and, surprisingly, Hurdle used him as a lefty specialist some of the time. That didn't last, as Watson is very effective against all hitters.
Jared Hughes (66 G, 2.85 ERA, 2 Sv): Hughes served mainly as a long man, as the Pirates didn't have a Carrasco or a McCutchen in 2012. Hughes' role later evolved into 6th/7th-inning-GIDP-guy, as the Pirates focused more often on having a potential spot starter in the long relief role.
Chris Resop (61 G, 3.91 ERA, 1 Sv): Resop continued to give the Pirates a solid middle reliever, but his K/9 dropped from 10.2 to 5.6. Maybe because of that, or because they didn't want to pay him an arbitration salary, the Pirates traded him to Oakland for marginal reliever Zach Thornton. Resop fell apart with the A's.
Brad Lincoln (28 G, 2.73 ERA, 1 Sv): The former first-rounder made a few starts, but spent most of the first four months coming out of the bullpen. He pitched very well as a reliever, then went to Toronto in a deadline deal for Travis Snider.
Evan Meek (12 G, 6.75 ERA): Meek opened the season with the Pirates, but his velocity was down and he had trouble throwing strikes. He was sent down and spent much of the season in AAA. The Pirates outrighted him late in the season and he left as a free agent in the off-season.
Chris Leroux (10 G, 5.56 ERA): Leroux spent much of the season on the disabled list with a muscle strain. The Pirates eventually outrighted him, then called him up in September, but he didn't pitch well. He pitched two games for the Pirates at the beginning of the 2013 season, then was outrighted and became a free agent.
Bryan Morris (5 G, 1.80 ERA): Morris got a September callup.
Justin Wilson* (8 G, 1.93 ERA): Wilson got a one-day callup in August, then came back for the month of September.
Juan Cruz (43 G, 2.78 ERA, 3 Sv): Cruz had a history of missing both bats and the strike zone. The Pirates signed him to a minor league deal and he made the team out of camp. This was before the days of, "Ray can fix him," and it turned out Ray couldn't, which probably serves as a useful reminder. Cruz put up a nice ERA, but he had a WHIP of 1.63 and xFIP of 4.49. He missed some time with shoulder trouble and the Pirates released him in August.
Chad Qualls (17 G, 6.59 ERA): The Pirates obtained Qualls in a deadline deal from the Yankees for Casey McGehee. Qualls pitched reasonably well; the bad ERA resulted from a strand rate of 31.3%. His xFIP was 3.94. He moved on after the season and became the subject of one of the greatest gifs in the history of the internet.
Doug Slaten* (10 G, 2.77 ERA): The Pirates signed Slaten to a minor league deal. He was a soft-tossing lefty who had a fair amount of major league experience, mainly as a LOOGY. He pitched very well in AAA, got called up for a month at mid-season, then went back to AAA. Hurdle oddly used him as a long man. Slaten managed a good ERA, but his xFIP was 5.37. He never pitched again after 2012.
Hisanori Takahashi (9 G, 8.64 ERA): The Pirates acquired Takahashi from the Angels, for whom he'd been pitching decently, on a waiver claim in late August. He struggled the rest of the way and was released after the season.
In Neal Huntington's earlier years, the Indianapolis bullpen was primarily made up of minor league veterans who weren't likely to have any long-term role in the organization. The 2010 bullpen was an example. The 2011 bullpen was made up heavily of prospects on their way up. In 2012, the bullpen was comprised more of pitchers with some upside, as opposed to pitchers who primarily figured to help the AAA team win games. This included some minor league veterans: Wood and Slaten, who both got callups, and Jumbo Diaz, who didn't. He'd always had great velocity but was held back by his prodigious girth. (Diaz finally got into good enough shape to reach the majors with the Reds in 2014.) Dan McCutchen Evan Meek and Chris Leroux spent most of the season there, trying to work their way back to Pittsburgh. Moskos did the same for a couple months, but ended up with the White Sox when the Pirates removed him from the 40-man roster. Bryan Morris spent the season in AAA until his September callup. Duke Welker got promoted from AA partway through the season. Welker was yet another tall right-hander who'd struggled as a starter, but got a big velocity boost, to the upper-90s, when he moved to relief. (Justin Wilson spent the year in the AAA rotation.) Indianapolis also had Kris Johnson*, a former top Red Sox prospect who finally made progress after joining the Pirates. He got promoted after pitching well in AA and made it to Pittsburgh in 2013.
This was Huntington's first good bullpen. It was also very stable, with five pitchers filling roles all year, and the Pirates were able to add two September callups who'd be contributors further down the road. The one thing that didn't work out well was late-season, veteran additions. Qualls was just OK and Takahashi was bad. For whatever reason, maybe having more time to accumulate scouting information, the Pirates got better at this later on.
You could make a good argument that the 2013 bullpen was the most talented one the Pirates have had under Huntington. They had two outstanding closers, two dominating lefties, two good long men, and two good, young pitchers (Bryan Morris and Jared Hughes) who didn't pitch up to their abilities due to inexperience and injury. They needed to do only a very limited amount of shuffling around, mainly as the result of an injury to Jason Grilli and a puzzling interest in Jose Contreras.
Jason Grilli (54 G, 2.70 ERA, 33 Sv): Took over as closer for the traded Hanrahan and was outstanding. Fanned 13.3 per nine IP. Grilli missed a month and a half in July and August, and was a bit shaky when he came back.
Justin Wilson* (58 G, 2.08 ERA): Wilson was another former starter who saw a velocity boost when he moved to the bullpen. He'd always been capable of reaching the mid-90s, but as a reliever he sat in the mid-90s and reached the upper-90s. He and Tony Watson gave the Pirates two lefties who were nearly as effective against right-handed as left-handed hitters. Wilson had almost no relief experience in the minors, but had an outstanding year for the Pirates.
Tony Watson* (67 G, 2.39 ERA, 2 Sv): Watson improved his control and became strictly a one-inning reliever. When Grilli was out, he moved into the 8th inning role.
Bryan Morris (55 G, 3.46 ERA): Morris started the season in AAA, but was called up for good at the end of April. He showed good stuff but was very erratic in middle relief; his ERA was a lot better than his xFIP, which was 4.34.
Jared Hughes (29 G, 4.78 ERA): Hughes was the odd man out early in the season, since he had options and the Pirates were carrying on an ill-advised flirtation with Jose Contreras. He ultimately struggled with shoulder problems that cost him a chunk of the season.
Mark Melancon (72 G, 1.39 ERA, 16 Sv): Not an overpowering pitcher, Melancon at this point threw mostly about 92-93, relying heavily on a cutter and curve, and getting groundballs at a very high rate. The Pirates seemingly relied partly on non-traditional stats like xFIP in acquiring Melancon after a bad year, as they had done with Hanrahan and A.J. Burnett. Melancon took over as closer while Grilli was out and, on the season, put up 2.5 fWAR, the third most of any reliever in MLB.
Vin Mazzaro (57 G, 2.81 ERA, 1 Sv): The Pirates acquired Mazzaro in a minor deal with Kansas City after he'd been designated for assignment. He didn't make the team out of camp, but was called up in mid-April when the Pirates gave up on Chris Leroux. He was a former top prospect who threw a 92-93 mph sinker and had a good groundball rate. He was very effective in middle and long relief for the Pirates. As per usual, they didn't get too attached; they outrighted Mazzaro before the 2014 season, called him up briefly, then outrighted him again. He cleared waivers each time, but finally chose free agency after the 2014 season.
Jeanmar Gomez (34 G, 3.35 ERA): Gomez had a history of being extremely hittable, but he did a remarkable job in a swing role, including eight excellent starts, after the Pirates got him for an Exicardo from Cleveland. The team's experience with Gomez, and with the loss of numerous starters early in the 2013 season, may have led them to place more value on having a long reliever who could move into a starting role.
Ryan Reid (7 G, 1.64 ERA, 1 Sv): Reid was similar to Tim Wood; a smallish RH reliever with fairly good velocity. He signed a minor league deal, pitched well in AAA, and got called up for a month in the middle of the season.
Stolmy Pimentel (5 G, 1.93 ERA): After acquiring him in the Hanrahan trade, the Pirates wanted Pimentel to be a starter, but he pitched in relief during a September callup. He looked outstanding in brief opportunities, showing mid-90s velocity.
Kyle Farnsworth (9 G, 1.04 ERA, 2 Sv): The Pirates signed Farnsworth in mid-August after Tampa Bay released him. A standard, hard-throwing reliever, he pitched well for the Pirates, subbing as closer when they became concerned about Melancon tiring out.
Mike Zagurski* (6 G, 15.00 ERA): Zagurski had a history of pitching well in AAA but poorly in the majors. The Pirates signed him to a minor league deal and he pitched well in AAA, so they called him up in late May. He also had a history of large platoon splits in the majors, but Hurdle didn't use him as a LOOGY. He struggled badly and the Pirates waived him a few weeks later.
Jose Contreras (7 G, 9.00 ERA): The Pirates signed the 41-year-old Contreras to a minor league deal and called him up early in the season, possibly because they lacked faith in Hughes and Morris. Contreras struggled with the strike zone and with back problems, and finally was released in July.
The Indianapolis bullpen was made up heavily of prospects and projects. Two of the mainstays were Vic Black and Duke Welker, both prospects capable of hitting 100 mph. Tim Alderson spent part of the season there before the Pirates finally gave up on him and sent him out in a minor trade. Another regular reliever was Erik Cordier, who was also capable of hitting 100 mph but who'd struggled his whole career to throw strikes. Veterans included Reid, Zagurski, Brooks Brown and Atahualpa Severino*.
The Pirates continued to get considerable mileage out of inexpensive, groundball-inducing relievers. Despite Hughes' struggles, Mazzaro and Gomez were very productive. It's not that the Pirates look for junkballers, as they clearly like velocity a lot, but they seem to be able to find undervalued pitchers who throw hard and don't strike out a lot of hitters. The team seems to defy the defense-independent pitching research; Hughes has generally had much better ERA than xFIP stats (dramatically so in 2014-15), and Mazzaro and Gomez also did during their time with the Pirates.
The Pirates' bullpen in 2013 was good enough that they didn't need to do much adjusting late in the season, even with the injury to Grilli. Their only veteran pickup was the free agent signing of Farnsworth. In fact, they actually traded away two very hard-throwing relievers, Black and Welker (as a PTBNL in Welker's case), in their waiver deals for Marlon Byrd and Justin Morneau. They did so again two years later, with Jhonathan Barrios, in order to acquire Aramis Ramirez. That may (or may not) say something about their confidence in being able to piece together bullpens each year.