Scott Diamond has struggled mightily this season' date=' with an ERA of 5.40 after last year’s stellar 3.54 ERA. Some of this regression was expected; not only did Diamond greatly exceed expectation but he also posted a 3.94 FIP in 2012. The real question is the cause of Diamond’s struggles this season: if he has truly taken a step back, expect his struggles to continue, and he may lose his spot in the rotation. However, if Diamond’s poor performance has been more a result of bad luck, there is a good chance he could rebound in the second half.

 

[b']The Bad:[/b]

Diamond is walking more batters, striking out fewer, generating fewer groundballs, and giving up more fly balls than a year ago. This displays that Diamond truly has struggled this season.

2012:12.6%K 4.3%BB 2.90K/BB 53.4%GB 25.6%FB 2.09GB/FB

2013:11.0K 4.9%BB 2.25K/BB 47.8%GB 34.2%FB 1.40GB/FB

 

What has caused this:

First there has been a difference in pitch selection. Diamond is throwing his fastball more and his curveball less than a year ago, which probably not a good sign for a soft-tosser. To make matters worse, he has lost some velocity on his fastball from a year ago. This could be a long-term problem for Diamond.

2012: 60% fastballs (89.4 mph) 29% curveballs

2013: 65% fastballs (88.2 mph) 23% curveballs

 

The Good:

Diamond is allowing fewer line drives this year, which typically leads to a lower BABIP, because players seem to hit around.700 on line drives (I’ve read varying statistics from several sources, but this seems to be the general consensus). In fact, only 12 pitchers in all of baseball are giving up fewer line drives this season.

2012: 21.0% LD

2013: 18.0% LD

Despite giving up fewer line drives than last year, Diamond’s BABIP has gone through the roof. In fact, Diamond has allowed the 6^th highest BABIP in MLB.

2012: .292

2013: .337

Another cause of Diamond’s struggles has been his inability to strand runners on base. Not only has his left on base percentage dropped significantly from last season, but his LOB% this season is the 9^th lowest in all of baseball.

2012: 73.3% LOB

2013: 65.7% LOB

 

What to expect going forward:

Diamond has clearly regressed this year. The bottom line is that the things he can control—strikeouts, walks, groundballs, flyballs—he isn’t doing as well as he did last year (with the exception of line drives). It is very possible that this is a result of the changes in Diamond’s repertoire, both pitch selection and pure stuff. This is a legitimate long term worry that could plague him going forward.

However, the severity of Diamond’s regression should not as extreme as it has been. This is largely the result of bad luck. As the season progresses, these trends should regress towards the league average and Diamond’s numbers should improve. However, it is unlikely that Diamond will return to his 2012 numbers unless he makes some changes to his pitch selection and adds some velocity to his fastball.