Here's the first round of my answers to your questions. There are a lot of great questions left, so I look forward to answering more of them tomorrow.
Long4Willie: Where do you think Radhames Liz fits on the 2015 team? Do you think he will be a starter or reliever, and if he's a starter, do you think he will be one of the starting five sometime during the 2015 season? Is he the replacement instead of signing Edinson Volquez? Lastly, how do you think he will do?
Nobody but the Pirates really knows the answers to these questions, and unless someone answers them definitively (not that the Pirates have to have answers at this point, and not that they're obligated to provide them if they do), Liz will be the Bucs' biggest wild card heading into spring training.
My guess is that the Pirates will use him as a reliever. They already have Gerrit Cole, Francisco Liriano, A.J. Burnett, Vance Worley and Charlie Morton for the rotation, with Jeff Locke as a backup plan in case Morton isn't ready. I don't see how the Pirates can start the season without Worley in the rotation, and even if Morton can't be in the rotation at the start, Locke is a very reasonable option there. Maybe Liz will be incredible in spring training, and if so I would be fine with giving him a shot, but otherwise, the Pirates already have enough decent options that they shouldn't need to start the season with a big question mark in the rotation.
That leaves the bullpen. Mark Melancon, Tony Watson, John Holdzkom, Antonio Bastardo and Jared Hughes are likely to win five of the seven slots, but Liz could take one of the others. That would make sense, too, given his history as a flamethrower with poor control. It will be interesting to see what happens with all the out-of-options pitchers, though -- Liz, Worley, Locke and Stolmy Pimentel are all out of options. As far as I know, it's not yet clear whether Liz's contract allows the Pirates to keep him under team control for six years (since his big-league service time is currently less than a year), or under what conditions. If they do, that could make him more likely to make the team out of spring training.
Pat_Meares: Assuming Morton is ready for opening day, who is the odd man out between Locke and Worley?
Locke. Worley was flat-out good last year in a way Locke never has been.
PedroPower: I predict a wRC+ of more than 140 for Starling Marte and greater than 105 for Gregory Polanco. Do you think I will be proven correct?
I'll go with no on Marte and yes on Polanco. Your numbers are both significantly ahead of Steamer's projections, but I like Polanco's chances of beating his.
Karp62: Given the Royals and Giants' success with the shutdown bullpens, the Astros setting a new RP market price for relievers and quality lefty relievers not being a fungible as righty relievers, shouldn’t the Pirates look to sign Tony Watson to an extension that buys out his arbitration years and perhaps one or two more?
To me, the lesson of the Royals' dominant bullpen isn't, "Relievers are extremely important and if you can find a good one, you need to commit to him," it's, "Relievers are extremely important but hard to project, so you need to commit to trying to find them." The core of the Royals' bullpen success in the playoffs was Greg Holland, Wade Davis and Kelvin Herrera, but only Holland entered the season as an obvious shut-down guy. Davis was a failed starter whose stuff played up in the bullpen, and I'm honestly not sure Herrera ever really was, or is, a shut-down reliever so much as a decent one who posted a nifty ERA last year and happened to carry his success through the playoffs. His SIERA last season was two runs higher than his ERA, so while he throws very hard, the statistical evidence to suggest that he's actually a dominant reliever isn't there. (Maybe he'll continue to improve, though -- he's only 24.)
There isn't anything there that should make the Pirates want to commit to Tony Watson for four years or more. They already control him for three, which is a lifetime in reliever years. Beyond that, we have little idea if he'll be good or not. Maybe this will be worth considering in two years or so, but even then I doubt it -- this is how small-payroll teams get into trouble. What the Pirates need to do instead (and they've already done a good job with this) is to try to find the next Tony Watson, or the next Mark Melancon.
KareemOfWheat: Are you sad Edinson Volquez agreed to terms with the Royals?
No. I try not to let the Pirates make me sad in general, but beyond that, I see the success Volquez had with the Pirates more as a reflection of the system the Pirates have in place to help pitchers, and not so much of Volquez himself.