Series preview: St. Louis Cardinals in town for 4 big games

It's hard to get to be baseball's second best team, and it's even harder to be baseball's second best team and be four and a half games out of first place, but that's where the Pirates find themselves as they begin a crucial four-game set tonight against the Cardinals. Here's what to expect from the team with the best record in baseball so far.

POSITION PLAYERS: .259/.323/.391. 13.4 fWAR, fourth in the National League. Quick -- name the top two Cardinals in position player fWAR. They're Kolten Wong and Jason Heyward, not who I was expecting. (Wong appears to have graduated from only beating the Pirates to beating everyone else, too.) Other than Matt Holliday, who's on the DL, the Cardinals don't have anyone having a banner offensive season. What they do have is lots of guys hitting well, and even more contributing defensively. Yadier Molina, Heyward and Jon Jay have been especially terrific in the field, although Jay now joins Holliday on the DL. This weekend, Heyward, Randal Grichuk, Peter Bourjos and Tommy Pham will man the Cards' outfield. With Matt Adams out for what appears to be the rest of the season, meanwhile, the Cards will go with some combination of Mark Reynolds, Xavier Scruggs and newly promoted minor league vet Dan Johnson at first base.

PITCHING: 2.62 ERA, 3.26 FIP, 3.54 xFIP. 12.1 fWAR, second in the National League. The Cardinals are behind the Nationals in staff WAR, but ... just look at that ERA! Look at it! The Cardinals have a good defense and are have been ridiculously stingy with runners in scoring position, so it's not surprising their team ERA is low. But what's most striking about the Cardinals' staff is its depth. Usually when you look at a team's pitching statistics at this point in the season, you see some pitchers at the top who are doing well, followed by a slightly larger number of pitchers at the bottom who have done very poorly. Those are the guys who aren't on the active roster anymore -- they're in the minors or on the disabled list, or they've been designated for assignment.

The Cardinals have used 19 pitchers so far this season, but no one stands out as having been a disaster. Sam Tuivailala pitched three innings and didn't do very well. Mitch Harris and Tyler Lyons struggled a bit. But no one has had that hard a time. In fact, the only other staff in baseball I could find that's enjoyed the kind of stability the Cards have is ... wait for it ... the Pirates, who've used 17 pitchers and haven't had significant problems. (Radhames Liz isn't very good, but if he's the worst guy to pitch on a staff in an entire season, you've got an awfully successful staff.)

The Pirates will miss Michael Wacha in this series, but the Cardinals' starting pitchers are going to give the Pirates a hard time. The closest thing the Bucs will get to an easy matchup is Sunday, when Francisco Liriano will face Tim Cooney. Cooney's a rookie and a soft-tossing lefty, albeit a pretty good one who made quick work of the minor leagues after being drafted in the third round in 2012.

On Thursday through Saturday, the Bucs face Carlos Martinez, Lance Lynn and John Lackey. (The Bucs will send Jeff Locke, Gerrit Cole and A.J. Burnett, respectively.) Martinez doesn't throw quite as hard as a starter as he did last year as a reliever, but he's still nasty. His greatest (read: only) weakness is walks, so if he offers the Pirates any, it would behoove them to accept. The splits on Lynn's peripherals suggest he's markedly weaker against lefties than righties, and he gives up his share of fly balls, so maybe he'll serve up a Pedro Alvarez homer on Friday. Lefties have also hit Lackey well this year. In general, though, these are tough draws.

OUTLOOK: The Cards' season so far has been defined by winning, but it's also been defined by injuries (and hacking, but we'll leave that aside right now). Just for this series, Adam Wainwright, Jaime Garcia, Adams, Holliday, Jay, Jordan Walden and Matt Belisle will all be out. Also, Wong is currently dealing with concussion issues, and it sounds like he could miss at least Thursday's game.

Still, the Cardinals keep flying, and the reason is their outstanding depth. Grichuk didn't begin the year as a starter, but he's hitting .260/.303/.526. Bourjos is good enough to start for most teams, but he isn't exactly a starter in St. Louis even after injuries to Holliday and Jay. Reynolds isn't a great player, but since Adams got hurt, he's stepped in and been competent. And then there's the parade of pitchers who come through St. Louis and perform just fine.

The Cardinals are 55-30. It's very, very hard to actually be that good, and they aren't. Their defense is strong, but the Cards' pitchers shouldn't be outperforming their peripherals by as much as they are. Of course, it's no surprise that a 2.62 team ERA is unsustainable. The Cardinals might not be able to maintain their ridiculous pace the rest of the way (and they haven't maintained that pace lately, with recent series splits against the Cubs and Padres and a two-game sweep at the hands of the White Sox), but they could fail to do that and still play like a garden-variety first place team. The Cardinals retain a 4.5-game edge on the Pirates as the two teams head into the second half. The Bucs can make up ground by taking three or four games this weekend, but either way, St. Louis will be a formidable opponent the rest of the season.