How is Mark Leiter Jr. suddenly a strikeout pitcher?

So yeah, it’s been twice now in the past two weeks that some team has totally abused a Phillies starting pitcher early in a game and BAM!, the Phils call in their secret weapon: long relief man out of the pen, Mark Leiter, Jr.

The first time was at Coors Field. The Rockies came out swinging on Nick Pivetta and pinned eight runs on him in 2.2 innings. Phillies manager Pete Mackanin came out with the hook and called upon Leiter. All Leiter did was throw 4.1 innings of two-hit ball, striking out nine and walking a grand total of none. He came in in the third and quickly proceeded to strike out the first four batters he faced, including Charlie Blackmon, DJ LeMahieu and Nolan Arenado.

His next outing was at home against the Mets. Vince Velasquez wasn’t able to find any control and was forced to leave the game due to “finger numbness,” allowing three runs on thre hits in his three outs of work. Again though, Leiter came in and gave a solid five innings, strikeing out seven while allowing one run on one hit.

Combined that’s 9.1 innings, 16 strikeouts, no walks and one run on six hits.

So, how did he do it?

For comparison purposes we’ll look at his last two very successful outings, the ones mentioned above, against his previous four MLB outings. Keep in mind that he took a trip to Lehigh Valley in the middle of the four unsuccessful appearances.

When you look at some of his metrics (courtesy of BrooksBaseball.com) you see one fairly obvious pitch that stands out when he was successful: the split-finger fastball. Not much changed with regards to it’s velocity or horizontal and vertical movement, but what did change was the frequency and situations in which he threw it.

In the four previous outings where he struggled, Leiter didn’t throw the split for a strike effectively.  He only threw it for a strike 24.14 percent of the time.

He also wasn’t throwing it in optimum situations.  When he was ahead in the count he threw the split 42 percent to left-handed hitters and a remarkably low 19 percent to right-handed hitters. Then, when he got to two strikes he only threw the split 45 perecnt of the time to lefties and 38 percent to righties.

And he was getting hit hard. The batting average against the split was a whopping .389. Batters were able to square it up and he didn’t miss many bats. The split had a whiff rate of only 28.5 percent.

So during those four previous outings he wasn’t throwing the split that often and when he did it wasn’t effective, in essence rendering him ineffective.

But then something changed.  It should be noted that in his first of the two remarkable outings, when he came in to relieve Pivetta in Colorado, Jorge Alfaro was behind the plate. Obviously Leiter and Alfaro worked together frequently throughout the minor leagues, so you could assume Alfaro had a more intimate knowledge of Leiter then Cameron Rupp, who caught Leiter a majority of the time at the major league level. It very well may have been Alfaro who got Leiter to start using the split more often and in key situations.

Leiter started throwing the split for a strike a lot more often, nearly twice as often in fact at 48.78 percent, up from that 24.14 percent mentioned above.

He also started using it when ahead in the count, 56.6 percent to lefties and a major increase to righties, from that 19 to 42 percent. When there were two strikes the usage also jumped, 62 percent to lefties and a massive 79 percent to righties, both up from 45 and 38 percent, respectively.

As a result, of the 16 strikeouts Leiter had during those two outings, 12 were on the split.  The batting average against dropped to a ridiculous .069 and the whiff rate climbed to 72 percent.

You can clearly see these are rather drastic changes creating rather drastic results. He’s using the split more, he’s using it in situations where it can be more effective and he’s getting strikeouts with it. It’s unclear how sustainable this is but if he can come even close to duplicating this success he’ll be a force, either out of the bullpen or as a starter.

Even better than Leiter turning it around could be that Alfaro may have been the impetus that caused it. Nothing against Rupp or Andrew Knapp, but it’s debatable that either has made any Phillies pitcher that much more effective.

If Leiter’s turnaround is Alfaro related then the Phillies could have another great catcher in the vein of Carlos Ruiz. A battery-mate who can help usher the team back into its next competitive era just as Ruiz did with Hamels and Moyer. A boy can dream, right?