Jon Lester is the unquestioned ace of the staff, yes, and John Lackey has revived his career to become a dependable middle-of-the-rotation arm once again. Felix Doubront is a talented, if inconsistent, option for the back end, and young arms like Brandon Workman, Allen Webster, Anthony Ranaudo, Matt Barnes and Henry Owens might see some MLB starts before 2014 is over, too.
Yet the biggest X-Factor in the Red Sox rotation will likely be one of Peavy or Buchholz: two talented, volatile and injury-prone pitchers. If both are healthy and effective, the Red Sox could easily boast one of baseball's best collections of starters. Should either prove ineffective or miss time to injury, the Red Sox will face an even steeper uphill battle as they seek to climb out of the 5-9 hole in which they find themselves after the season's first 14 games.
The question of which pitcher can make the biggest difference for the 2014 Sox largely boils down to a matter of upside vs. probability.
Let’s start with Peavy, who's coming off an excellent start against the White Sox Tuesday night, and who's been quite good so far this season. In 18.2 innings across three starts, Peavy has allowed just four earned runs, striking out 20 and walking 10. We're not accustomed to seeing such a high walk rate from Peavy, but he's featured a ton of movement on his pitches thus far, and his early results are encouraging, nonetheless.
For Buchholz, who makes his third start on Wednesday night against the White Sox, 2014 hasn't bee quite so kind. Buchholz's first start against Milwaukee was disastrous, as he gave up six earned runs in just 4.1 innings. His second outing against the Yankees was better, as he limited New York to two runs in six innings, striking out six.
Yet aside from some early observations—Peavy's stuff is good but he's struggling with control, Buchholz is leaving pitches up and is getting punished for it—we can't draw any predictive conclusions from these outings. To get a better idea of what to expect from these two pitchers in 2014, we must look at past performances instead.
Here are Peavy's and Buchholz's IP, ERA, K/9, BB/9 and HR/9 over the past three years, courtesy of Baseball Reference:
These are simple stats, but they do a good job of highlighting the differences between Peavy and Buchholz. As both pitchers have consistently lost velocity over the past three seasons, each has changed his repertoire. FanGraphs' PITCHf/x tells us that Peavy now relies mostly on a two-seam fastball, sprinkling in a four-seamer, a cutter and a changeup with only the occasional slider or curveball. Buchholz leans heavily on a cutter, four-seamer and changeup, relying less on the curveball that received so many accolades when he was a prospect.
To fully understand these pitchers, though, we must also look at a factor that's defined their careers as of late: injuries.
According to Baseball Prospectus' Injury History, Peavy has missed 106 game days due to injury in the past three seasons, suffering from ailments in his wrist, back, groin, ribcage and, most seriously, his shoulder. Buchholz, meanwhile, has missed a whopping 204 games over that same period, missing huge chunks of time with shoulder soreness and a stress fracture in his back.
If we assume that every five games equals one start lost, that means Peavy's been cheated out of 21 starts since 2011, while Buchholz has missed a stunning 40 starts. Those are scary numbers for the Red Sox—especially since shoulder injuries have been involved for both parties.
Where does this leave us for 2014? While Peavy and Buchholz are technically listed as the fourth and fifth starters for the Red Sox right now, when it comes to pure talent they should probably be listed third and second, respectively. Both pitchers are prone to the occasional homer—Peavy more so as a fly-ball pitcher—and neither are strikeout artists anymore. That being said, both possess the ability to post 4-WAR seasons and greatly improve Boston's playoff chances.
While Peavy will be 33 next month and Buchholz just 29, the former is actually a more durable pitcher than the latter, despite his reputation. Yet when both are healthy, Buchholz provides more per-inning value.
That means that determining who the more important pitcher is boils down to your personal appetite for risk. Buchholz, when he is on, is capable of pitching as Lester's co-ace, dominating lineups with his penchant for inducing weak contact and limiting walks. Peavy lacks that upside, but has a better shot of throwing 160 innings this season, despite his advanced age.
If Peavy and Buchholz can make 50 starts between them, there's an excellent chance the Red Sox will be headed back to October. If not, the Red Sox have collected plenty of pitching talent in the upper minors, but it's tougher to envision a road back to glory, nonetheless.