Introducing Luis Perdomo (Arigato Mr. Roboto)

My apologies for the attempt at humor in the title. I couldn’t resist using the end of today’s subject’s surname in a reference to a fantastic Queen Styx (sorry, Styx fans, my bad. I really thought it was a Queen song. Doesn't it sound like a Queen song? h/t to commenter Salti Cracker) song about...Japanese robots? What is that song about anyway?

Moving deftly back to baseball, thanks to this great article over at Fangraphs, I was introduced to the intriguing Padres reliever-turned-starter we are all here to talk about today. Well, at least that’s what I’m here for. I can’t speak for you.

Luis Perdomo grew up on the rough streets of Santo Domingo...ok, so maybe that’s farther back than we need to go. Here’s what you need to know. He’s a 23-year-old Rule 5 pick from last December, after the Cardinals cast him aside and the Rockies traded him to San Diego for basically nothing (player to be named later and cash). He throws a 94 mph fastball.

The Friars started him in the bullpen this year, before injuries forced them to bring him into the rotation. He hadn’t really earned the promotion at that point (that’s putting it nicely). Check out the following table, which shows his 2016 stats broken down three ways. First, his stats as a starter, then his reliever stats, followed by his stats in just the last four starts before the All-Star break.

Name	IP	ERA	FIP	xFIP	WHIP	BABIP	LOB%	GB%	SwStr%	K%	BB%	Soft%	Med%	Hard%
Luis Perdomo (Starter)	35.1	6.11	4.31	3.32	1.73	0.378	64.30%	66.10%	11.90%	18.90%	6.50%	22.80%	48.80%	28.50%
Luis Perdomo (RP)	29.2	9.1	5.47	4.75	2.26	0.426	60.70%	51.80%	8.80%	15.60%	10.40%	14.20%	52.20%	33.60%
Luis Perdomo (last 4 starts)	23	5.09	3.83	3.01	1.65	0.372	65.10%	65.80%	12.90%	19.40%	5.60%	22.20%	49.40%	28.40%

You can see his relief experience was not good. An ERA over 9 in almost 30 innings usually gets you sent to AAA, especially if the team has almost nothing invested in you. Instead, injuries to guys like Tyson Ross and Robbie Erlin forced the Padres to put Perdomo in the rotation. As you can see, the results have been better, but the ERA itself still hasn’t been good. That’s bad for the Padres, but not necessarily bad for fantasy players.

His terrible ERA so far masks a guy that might be a sleeper for deep leagues (and maybe more later on). Look at his xFIP values, his crazy swinging strike rates as a starter, that good velocity, his good walk rate, and the elite ground ball rate. A very unlucky BABIP AND strand rate (LOB%), along with a very high HR/FB ratio (22.7%) form a trio of bad luck that has led to his bad ERA. It is rare for a pitcher to be unlucky in all three of those stats at once. League average BABIP is around 0.300, LOB% is about 73%, and HR/FB is 12.9%. You can see how far from average he has been. This all screams positive regression.

If that regression maxes out, we could see something like the xFIP in his last four starts. That would be a very good ERA when combined with his great strikeout stuff. Digging deeper, as I usually do, here are the swinging strike rates and ground ball rates for all four of his pitches.

Both his two-seamer and curve are well above average pitches. The two-seamer gets both swings and misses and ground balls at a high level, while the curve is a good out pitch. The four seam is just mediocre, but does get a good number of grounders. The change-up is also pretty mediocre. He’s got two great pitches and two others to at least complement them with. That’s a good start.

I wanted to find out why he improved so much moving from the bullpen to the rotation, so I headed over to Brooks Baseball and poked around a bit. Here are the graphs I found:

The first one is just to show that he started throwing his excellent two-seamer in place of his four seamer, which he almost completely abandoned. Also, Brooks calls his curve a slider, or Pitch F/X calls his curve a slider, depending on who you ask. He increased the two seam usage every month this season and decreased the four seam use every month. That is a clear intention to hide his bad four seam and it seems to be working.

The second graph is there to point out that, while his fastball velocity has remained constant, his secondary pitches have slowed down, perhaps intentionally, to get more differentiation in speed between his pitches. His change-up, especially, was only 4 mph below his fastball and is now 7 mph slower. That is usually a very good thing, unless you are Felix Hernandez. He’s trying to make his change-up better. This change, like the two-seam change, coincides well with his drop in xFIP and improvements in swinging strikes.

Graph numero 3 shows another big change he made: he simply moved 6 inches on the rubber toward first base. There is such a distinct transition in the graph that it was clearly a conscious decision. Since it coincides with all these other changes, it is unclear how much a role it played in his improved performance, but it could be part of it.

The graph in position 4 exists only to display what seems to be a deliberate strategy to slow down his change-up the third (and second, a little) time through the order, perhaps to give hitters a different look. It’s a minor thing, but still a thing.

We have reached the final graph! This one doesn’t really tell a clear story like the others. His four seam and change-up whiff rates jump all over the place, while the others are pretty steady. I don’t have any insights here, just thought it was worth including.

So, let’s sum things up. Perdomo was a nobody for most of this season, and probably still is in most fantasy leagues. However, his recent changes, along with his existing velocity and room for improvement (he’s still only 23!) have made him into a fantasy sleeper. He’s only for deep leagues so far since we only have 35 innings as a starter to look at, but he could quickly move to 12-team relevance. He’s got almost everything I look for in a starter: high SwStr%, high GB%, low walk rate, mid-90s velocity, xFIP below 3.5.

There’s still a chance that he ends up like Robbie Ray or Drew Smyly in the "great raw stuff, but bad results" group and keeps putting up ERAs well above his xFIP and SIERA, but I’m betting on him regressing down close to that xFIP. I snagged him in my deep dynasty league, where starters are very hard to find, and I suggest you take a look and see if he might be a good addition to your team, too. This might be the most words ever written about him, but it’s been fun. Tschus!