Aaron Sanchez's Move to the Bullpen Makes Sense, Even If It Doesn't

Since 2011, his first season as a full-time big leaguer, Craig Kimbrel has been the best reliever in baseball, according to FanGraphs' version of Wins Above Replacement. Thirty-two starting pitchers have delivered more value to their teams over that span than Kimbrel, who has been worth 12 WAR.

The tenth-best reliever in all of baseball over that span has been Wade Davis of the Kansas City Royals, at 5.8 WAR. A total of 102 starters have provided that much value to their clubs over the same period.

Kimbrel is an absolutely spectacular pitcher in short bursts. He has accumulated those 12 wins in just 304 innings—a number that 166 pitchers have exceeded. Of the pitchers who've been more valuable than him since 2011, the closest one to his innings total is the Rangers' Yu Darvish, with 12.6 WAR over 545 1/3 innings.

On one hand, what that tells us is that a best-in-the-damn-world reliever can be astonishingly valuable, and that's without even considering the all-the-time pressure of the high-leverage innings that go with the job. Few teams can boast more than one starting pitcher who has been as valuable as Kimbrel. Even rarer, though, as we can see from the drop-off to a "mere" Wade Davis (who, note: is awesome) is a Kimbrel himself.

What this is a roundabout way of saying is, even obvious top-tier relievers like Davis simply don't pitch enough innings to make the kind of impact that mid-rotation starters do, and a pitcher who might otherwise be something on the order of an above-average starter, or better, truly needs to be Kimbrel-like if it's going to be worth moving him to the bullpen.

It's for good reason, then, that the usual baseball adage is that you let a pitcher start until he demonstrates that he needs to be moved from that role. And yet that's exactly what the Blue Jays are doing with Aaron Sanchez, who will be a reliever when he returns from a rehab assignment after injuring a lat muscle in early June.

To those Jays fans attuned to the industry's feelings about relievers it maybe seemed an odd choice, as well as those seeing Felix Doubront still in the club's rotation. And those remembering the great strides Sanchez seemed to be making as a starter in the early part of the season. Not only were some of the more superficial results getting better—he sported a 4.26 ERA heading into his May 19th start, then posted a 2.57 mark over the next four—he walked 7.3 percent of batters faced over his last four starts before hitting the disabled list, compared to 16.9 percent in his first seven, while maintaining a top-of-the-league groundball rate and a solid-enough strikeout rate.

A perfect starter he wasn't, but it seemed like a top prospect long billed as someone with front-of-the-rotation potential was blossoming into something that could be both useful in the near term and even better down the road.

In a vacuum, that the Jays are making the wrong decision here would be rather obvious. Unfortunately, the Jays don't have the luxury of operating in a vacuum. Closing out wins for their bullpen has been maddeningly difficult, with 20-year-old rookie Roberto Osuna being the club's only truly reliable reliever over a sample of more than a handful of innings (though another rookie, Bo Schultz, is getting there, and Liam Hendriks had a nice run until his last two outings—his only two so far in the month of July).

Sanchez was a terrific reliever when he was called up by the Jays at the end of last season. He basically discarded his slider and change, and cut his curveball useage from 25 percent in July to almost nothing, simultaneously moving from throwing 40 percent sinkers and 30 percent four-seam fastballs at the beginning of his call-up to 87 percent sinkers in September.

His stuff plays up in the bullpen to tremendous effect, with both his four-seamer and sinker averaging 97.6 while in the role last year, but 95 this season, as he's been forced to conserve energy in order to maintain a steady velocity throughout his starts.

That certainly doesn't automatically make him a Kimbrel or a Davis. In fact, the Jays were given a reminder Tuesday (just as they were announcing that they'd taken a flyer on bolstering their right-handed relief corps with the minor league signing of former Tiger and Yankee Joba Chamberlain), when Sanchez made his first appearance as a reliever of the season in a rehab game for Buffalo, throwing just 11 of his 24 pitches for strikes, allowing two unearned runs in the process. Sanchez walked 57 batters over 100 1/3 innings in the minors in 2014, but just nine over his 33 in the majors—an impressive turnaround, but one that always felt tenuous, especially when walks became a problem for him again early this year.

But the ferocious sinker still has so much potential that the Jays considered moving Sanchez to the bullpen from the outset of this season, until Marcus Stroman's injury rendered any discussion of that moot. It's something none of the Jays' other starters could bring to a relief role—someone like Daniel Norris included. There is plenty of talent there, but not the kind of overpowering stuff that typifies a late-inning arm.

It's not the ideal spot for Sanchez. It's not the ideal spot for his long-term development—he'll likely shelve just about everything but the sinker again, though with the nearly two months he's spent on the shelf, it's not likely he'd be able to build his arm up beyond the 133 1/3 innings he threw last year (which was another reason to be wary of sending him to the bullpen in April). But it's certainly ideal for the 2015 Blue Jays.

With Doubront almost certainly to be supplanted in short order by either Norris or, ideally, someone obtained in trade—and Mark Buehrle and Marco Estrada pitching extremely well of late, R.A. Dickey and Drew Hutchison entrenched in the Jays' rotation (if maybe dubiously)—going ahead and sending Sanchez to the bullpen actually makes a lot of sense. Even if it doesn't.