Scott Diamond's first start wasn't great. He survived the first four innings pretty well, but we've seen Diamond deal when it's on the hill. And on the 13th against the Mets, he wasn't dealing. And when his luck finally ran out, or when he just tired that extra bit, or when the Mets bats caught up to him - however you want to look at it, his day was over. Diamond only recorded one out in the fifth, and that was just because Ike Davis tried to turn a single into a double.
Yesterday afternoon, however, Diamond looked better. Chicago's offense isn't one of the league's most dangerous, but you have to give credit where it's due. If Alejandro De Aza hadn't been on base three times yesterday, it's unlikely the White Sox would have scored at all.
For pitchers like Diamond who do not have overwhelming stuff, location is key. Movement can be good or bad on these terms, and can be the difference between ball four and tying someone up enough to induce a ground ball. On Sunday, Diamond was in the latter group. Thanks to the good folks at Brooks Baseball, we can examine a few charts and graphs that will illustrate in part the difference between his start on April 13 and his start yesterday afternoon.
First I wanted to show a chart that illustrates pitch type speed (fastball, changeup, curve) and spin axis. Typically, spin axis will affect break.
In the case of his first two starts, the biggest difference we see here is that the breaking ball had a much more dramatic angle of spin. The greater the angle of spin, the higher the Magnus Force reaction, the more effective a pitch should be in terms of break. While axis isn't the only factor in determining break, it's a big one.
Another part of the equation is spin. In the charts below the values on the Y axis change, but two things stand out. First, the fastball was hitting between 1250 and 2000 rotations per minute in Diamond's start on the 13th. Compare that to a range of 2000 to nearly 3000 RPMs yesterday afternoon. Second, look at the drastic difference in RPMs on his curveball.
On the 13th, Diamond's curve not only didn't have the axis to help him with movement, but his RPMs were sitting right around 400.
Yesterday, his curves were getting 500 to 1000 rotations per minute. If a pitch at A miles per hour is achieving X RPMs, a pitch at the same velocity with X * 2 RPMs will have twice the break. Essentially, Diamond's curveball on Sunday was twice as good as it was on the 13th. And his fastball had more movement as well.
Better pitches don't always lead to better results. Some days a lineup will eat a pitcher alive regardless of his stuff. And sometimes, more break won't mean better stuff anyway. A great break on your curve or slider, or more movement on your fastball, won't matter if you can't hit your spots.
In yesterday's case, Diamond had the best of both worlds.