Is Jon Lester Injured or Just Tired? Or Neither?

Jon Lester surrendered seven runs against a weak Tampa Bay offense Wednesday night, prompting questions about the normally consistent lefty’s health.

After the poor outing, Lester emphasized that there are no health concerns.

But sometimes players don’t want to admit they are injured, especially ones with the ultra-competitive, no-BS attitudes like the one Lester exhibits. Excuses are never made. I’ve heard it before…

Thankfully, data doesn’t withhold the truth. There are instances when a pitcher’s release point drastically changes or velocity sudden drops, sort of like an ambulance blaring through a crowded urban environment. For Lester, there were indeed warning signs prior to being placed on the DL.

Whereas Lester’s been the epitome of steadiness throughout his tenure as a Cub, three starts prior to being shut down, his horizontal release point suddenly got closer to his body. It’s such a blatantly obvious change that I don’t have to highlight it below.

Lester’s horizontal release point change coincides with the timeline he hinted at feeling fatigued. If we assume that this change in horizontal release point is an indicator of fatigue, we can use it in the immediate future to determine whether or not Lester’s worn out.

The good news coming out of his most recent start is that Lester didn’t exhibit the same issues against Tampa as were evident immediately prior to his DL stint. The x-axis below is Lester’s horizontal release point from Wednesday’s start. Notice how the cluster of dots hover right over the “3,” not the 2.5 range we saw during his fatigue period in the above graph.

So is Lester injured? The data shows no evidence of fatigue or discomfort, nor does the eye test. Well, Lester certainly didn’t look great, but at least some portions of that uber-subjective series of exams are not damning

“He’s not saying anything,” Joe Maddon said after the game. “I don’t see any grimace and I don’t see any like hitch in the giddy-up. I don’t see anything. Since he’s come back, he’s had some wins, but none of them have been necessarily Jon Lester sharp.”

Should we feel confident about Lester’s effectiveness going forward? Actually, yes, I think so. He certainly hasn’t pitched well, but if he’s truly healthy I have confidence the kind of robotic mechanics that have given the Cubs ace some of the league’s best tunnel ratings. 

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