Pitchers on the Upswing
Using JA ERA trends to spot pitchers performing better of late
I made my own version of a SIERA-like stat for the dashboards and for content here at MLB DW. This all happened last October while most people weren’t paying attention. But it’s detailed here:
Long story short, it’s SIERA but with SwStr% replacing K% and Ball% replacing BB%. Slightly more powerful with small samples, but nothing groundbreaking, and it will not beat SIERA’s predictiveness after you have a 5+ start sample to work with.
But I’ve already proven Ball% to be more predictive of future BB% than current BB%, so it’s an upgrade in that regard. But it’s not the case with K%. Current K% (given a decent sample) will predict future K% better than SwStr%, but they’re close.
It’s fun to have our own metrics here, and I like JA ERA, although I do admit it could use a better name.
So let’s look into the data to see which batters are improving most rapidly in this regard. I think we’ll find some nice SPs to target on waivers or via trades.
This is also pretty useful in our favorite game, DFS. Roki Sasaki and Ben Brown, for examples, have been cheap lately and we’ve been pounding them into our lineups with great success. We’re getting ahead of the price curve. Same for betting. Sasaki was even money at over 5.5 strikeouts before the start against the Angels where he was obviously going to smash (easy to say in hindsight!). So we have all kinds of reasons to know this information I’m about to give you.
I’m looking at JA ERA over the last three weeks and comparing it to what every guy had before that.
Reid Detmers
First 9 starts: 3.87 JA ERA
Last 4 starts: 2.37
Detmers has a 36.5% K% in his last four starts. With a 7.3% BB%, that’s a 29.2% K-BB%. He seems to have finally figured something out here. And it’s been a long time coming, because he’s had runs of great peripherals as a starter before. The talent wasn’t the question, it was just the execution. And we’re seeing that this year.
Jack Flaherty
First 9 starts: 4.72
Last 4 starts: 3.52
I’m writing this before his Sunday start (June 7), but he’s been one of the buy-lows screaming the loudest. But people don’t want to believe in Flaherty!
Maybe there’s good reason for that. But a 29.5% K% with a 2.3% BB% in his last four starts (not counting whatever he does on the 7th today) shows you that the guy can really get the job done. He’s a fly ball pitcher, which is one of the reasons he gets himself into trouble, but a K-BB% above 20% heals most wounds.
UPDATE FROM JUNE 7TH: Another five-inning outing, this time giving up three earned runs. But seven more strikeouts to just one walk.