Not only are there a lot of free agent starters available, but a good number of them throw from the left side. The Diamondbacks desperately need a southpaw starter, as left handed batters hit .285 with 87 homers off of last year's staff. Internally, only Evan MacLane, the southpaw acquired in the Shawn Green deal, has a shot at making the rotation from the left side out of spring training. Just MacLane, Doug Slaten, and Randy Choate are lefty possibilities out of the bullpen.
The top tier available lefties are Barry Zito, Andy Pettitte, and Tom Glavine. Zito has been living off of a pitchers park and an excellent defense behind him for the past few seasons, and is going to be grossly overpaid by some team this offseason. Pettitte generally handles right handed pitching better than those who stand in the first base batter's box, so he's not a particularly good fit. The soon-to-be 41-year old Tom Glavine decided not to exercise a player option of $7.5 million to stay with the Mets, so may be expecting more money than is reasonable. Josh Byrnes is simply not going to overpay for this supposed cream of the crop.
So if he's going to fill this vacancy via free agency, Byrnes will have to take a chance on a pitcher with some question marks. Ted Lilly was the Miguel Batista of the Blue Jays' rotation last year; some good starts, some bad starts, but a lot of innings pitched and a good overall ERA. Yet Lilly is only one year removed from a 5.56 ERA season, so he is hardly a safe bet. Bruce Chen is the epitome of a good year/bad year type of player, but last season was his worst yet, and I don't think that the Diamondbacks want to get that risky.
The two most likely free agent lefties to sign with Arizona are Mark Mulder or Randy Wolf. Points in Mulder's favor are that he is just 29, resides in the Phoenix area, has been a workhorse in the past, and has allowed just two runs in three career starts against Arizona (all wins). However, he has had significant injuries the past two seasons, resulting in widespread ineffectiveness, and is an extreme flyball pitcher, so might not succeed in the dry heat of Arizona even if everything's right with him. Wolf has also had injuries these past two seasons, but should come at a cheaper price, has also handled the Diamondbacks well, and has been more effective lately when healthy enough to pitch. He's also used to pitching in a home run park.
Besides saving money, the other advantage to acquiring a high-risk starting pitcher is that if he gets injured or completely flops by May, the Diamondbacks should have a better idea of which of their high-level pitching prospects would be ready to replace them. To get another pitcher besides Livan Hernandez who's good for 200 innings and a 5.00 ERA would be counterproductive, because he might actually clog up a rotation spot for a more effective pitcher.
Finally, Byrnes could fill the rotation spot via a trade. Given the fact that the market for starting pitchers has exploded over the past three seasons, there are a lot of pitchers still signed under old deals who look like great bargains in this new market. The problem is that the General Managers who signed them know this, and won't give them up without a fight. Sorry to disappoint the fans of 29 teams who are all certain that Dontrelle Willis will be in their club's rotation by the spring, but Larry Beinfest isn't going to trade Willis for anything less than a genetic replica of Walter Johnson.
One possible option is Mark Buehrle, who is under contract for $9.5 million. The White Sox need to clear room in their rotation for Brandon McCarthy, desperately need to re-stock their minor league system, and have dealt with Josh Byrnes twice before already. However, even though you might have to pay as much money for a less effective Ted Lilly, Randy Wolf, or Mark Mulder, you would not need to give up any talent in order to sign them. While the Diamondbacks do have surplus young talent at several positions, they also gave themselves a lot of payroll flexibility last season.
They are one of the few fortunate franchises to have enough resources to improve themselves either through trades or through free agency this season. Josh Byrnes has cleaned up the mess that he inherited, and will be dealing from a position of strength for the first time in his Arizona tenure.
Read more from Keith Glab at BaseballEvolution.com