From diamond in the rough to just plain rough.

For Twins starter Scott Diamond, it’s been a tale of two seasons. One of the lone bright spots on a 2012 Twins team that lost 96 games en route to a second straight last place finish in the AL Central, Diamond managed to go 12-9 with a 3.54 ERA over 173 IP, good enough for 2.3/2.4 WAR depending on your preference. Heading into the offseason, he was the only Twins starter assured of a spot in the 2013 rotation, and was generally expected to be the staff ace in just his second full season in the bigs.

And then 2013 happened. Diamond started the season on the DL following minor offseason elbow surgery, and things have been ugly since his return. Following his most recent shellacking Sunday against the Indians in which he lasted just 4.2 innings, Diamond is now 5-9 while sporting a 5.53 ERA. The southpaw has been terrible against lefties (.343/.398/.646), and not much better against righties (.301/.344/.476). He has completed six innings in just 2 of his last 13 appearances, and opponents are slashing a ridiculous .452/.520/.845 against him the third time through the lineup. He’s been bad on the road, and even worse at Target Field. Simply put, he’s been ****ty no matter how you cut it.

So what the hell happened? A closer look at Diamond’s 2012 numbers reveal that he probably wasn’t as good as his peripherals would indicate; his 3.94 FIP and 3.93 xFIP suggest his ERA should have been about a half a run higher than it was. He compensated for a severe lack of strikeouts with a solid BABIP and strand rate, by inducing a lot of ground balls, and by walking almost no one. In short, Diamond probably pitched about as well as anyone could have hoped given his lack of pedigree and merely average stuff, and some regression should have been expected.

Enter regression. Diamond’s 2013 numbers are significantly worse across the board. Not surprisingly, his BABIP (.319 vs. .292) and strand rate (67.4% vs. 73.3%) have come back to earth. He is also inducing far fewer groundballs (46.2% vs. 53.4%), and fly balls are leaving the park at a much higher rate (14.2% vs. 11.4%). Further, his already low strikeout rate (4.68/9) is now the worst in MLB (4.03/9), and it has been accompanied by an increase in walks (2.53/9 vs. 1.61/9). It all adds up to a 5.20 FIP and 4.68 xFIP, which somehow are actually better than his league-worst ERA.

In looking at his PITCHf/x data, Diamond’s problems appear to stem from the reduced effectiveness of his curveball. Easily his best pitch in terms of pitch value in 2012 (3.3 runs above average), it has become been a net negative pitch in 2013 (-5.5). Perhaps as a result, Diamond is throwing it much less often this season (23.9% down from 29.0%). Those curveballs have become fastballs in 2013, and unfortunately, Diamond’s fastball is nothing to write home about. In fact, it produced negative value last year (-3.7) and has been even worse this year (-9.6), likely due in part to a slight decrease in velocity (88.3 vs. 89.3). Looking at Diamond’s release points on Brooks Baseball (and with the obvious caveat that I am a pitching novice), it appears that he’s not getting on top of the ball as well this year. His curveball also appears to have flattened out since last season, with more horizontal but less vertical break. Whatever the reason, his new approach has rendered him ineffective as a starter this season.

So which is the real version of Diamond: 2012 or 2013? Truthfully, the answer probably lies somewhere in between, though I lean more towards the latter season. He obviously has more ability than he’s shown, but he’s likely nothing more than a back of the rotation starter on a contender. Regardless, without some serious immediate improvement, a demotion to AAA Rochester is likely on the horizon. Paging Nick Blackburn. #p2c

Originally published on pitching.2.contact