What is going on with Pedro Strop?

Pedro Strop is one of the best relievers in Cubs history and his contributions to the Cubs since 2013 have been well documented on BCB and other sites.

But something is off in 2019. It’s obvious if you glance at Strop’s game logs in 2019. It’s obvious if you watch the team play. So last night after Strop gave up four hits and three earned runs in the eighth inning to blow the Cubs opener against the Giants I spent some time looking at his pitches and some numbers to see if I could figure out what happened to turn Pedro from one of the most effective relievers in baseball to a totally unreliable option in the later innings.

One note, all I’ve got here is data, pitch maps and charts. They offer a lot of insight about pitch location and effectiveness. But they don’t tell us very much about why those pitches are less effective.

There are a lot of possible explanations for Strop’s problems in 2019. It is well documented that home run rates are up because of differences in the ball. It’s possible that Strop’s pitches are being adversely affected by those changes which is contributing to him being hit harder. Alternatively, Strop has dealt with multiple hamstring injuries over the years and it’s possible that he’s dealing with lingering effects from the injury he suffered earlier this season. Finally, Strop is 34 years old and it’s not uncommon for pitchers to start to decline around that age.

I’m going to leave it to the Cubs coaching staff and trainers to figure out exactly what the root of the problem is, but I feel pretty confident in saying the following: Chicago — we have a problem.

Velocity and pitch usage

Strop has been an incredibly effective pitcher since 2013. During that time he relied mainly on his slider and sinker throwing them 38 and 35 percent of the time respectively. He’d mix those up with a four-seam fastball that he threw about 16 percent of the time and a cutter that he threw eight percent of the time.

He’s changed that mix considerably in 2019. This season he’s using his slider 40 percent of the time and bumped up his cutter usage to about 20 percent of the time. His four-seamer is another 19 percent and his sinker is only used about 14 percent of the time. You can see this visually here:

Brooks Baseball

I think it’s pretty clear this isn’t Strop’s ideal pitch makeup. Aside from throwing different pitches the other thing that jumps out pretty clearly in his charts is the decline in his fourseam fastball velocity. He used to have about a 12 mph difference between his fastball and his slider, in 2019 that difference is down to about 10 mph. Interestingly, that is a gap that is similar to the end of last season when Strop was playing hurt.

Brooks Baseball

Outcomes

If you watch Cubs baseball regularly the next series of tables and graphs are not going to be a surprise to you. The result of Strop’s different pitch makeup and velocity has not been great. Pedro is getting hit and he’s getting hit hard. This is easiest to see in his Statcast numbers by year from Baseball Savant:

Baseball Savant

The number that immediately jumps out at me is the number of barrels Strop has given up in 2019 relative to his career. That is a huge jump and indicates he’s being hit much harder than normal. You can see the same thing in this chart tracking opponents SLG on his pitches by year:

Brooks Baseball

This also goes a long way towards explaining why he’s gotten away from using his sinker, since it’s been hit really hard in 2019, but his new mix isn’t close to as effective as his previous mix.

The good news is, he’s had stretches like this before and recovered. It’s possible he can do that again.

Location

The last thing I looked at was Strop’s pitch location per Statcast data. To get a better idea of changes I looked at both 2018 and 2019 to see where there were key differences

Baseball Savant

Baseball Savant

Two things stood out to me. First, the four-seam fastball was more effective in 2018 when it was clustered inside more. That has not been the case in 2019 where the pitches have been spread more evenly across the zone. Second, you can literally see him throwing his sinker less and it appears as though the pitch is moving similarly to 2018. The effectiveness of that pitch likely has less to do with location than some other factors.

Takeaways

The Cubs bullpen improved considerably with the addition of closer Craig Kimbrel but now they seem to have a problem bridging the gap between the middle innings and the ninth. Strop is clearly experimenting with different pitch makeups to compensate for a less effective sinker and a slower four-seam fastball, but the Cubs don’t have anywhere near the divisional cushion they need to let him continue those experiments in the eighth inning. While the rumors that Brandon Morrow has started facing live batters again are promising, he’s still out until at least mid-August. In the interim it may be time to let Steve Cishek or Brandon Kintzler try their hand at setup man duties in close games in the eighth.