Edwin Diaz showed progress in September, is it enough to trust him in the playoffs?

Edwin Diaz‘s tenure as a Dodger could not have gotten off to a much worse start. Fresh off a three-year, $69 million contract to be their new shutdown closer after their last free agent shutdown closer (Tanner Scott) flopped in 2025, Diaz instead somehow did even worse than his predecessor.

In his first seven outings, he pitched six innings, giving up seven runs on nine hits and five walks for a cool 10.50 ERA. Diaz was then scheduled to miss months after he underwent surgery to remove loose bodies from his elbow on April 20, which in a way was maybe a bit of a relief in that it gave him an excuse for his performance. Well, he then returned on July 29 and looked even worse, going 7.2 innings in nine outings and surrendering 11 runs on 16 hits and five walks for a 12.91 ERA. Diaz was promptly placed back on the IL with neck inflammation on August 18, and it sure looked like that might’ve been an end to a lost season for him.

Then a funny thing happened down the stretch in what looked like borderline courtesy appearances for a veteran.

The most remarkable thing about Diaz’s return is he was also terrible in his AAA rehab outings, giving up six runs in 4.1 innings across five appearances down there. But upon finally returning to the majors on September 18, he was largely flawless and seemed to grow in confidence with every outing, pitching five shutout innings, striking out nine and allowing just a single walk and hit. That performance seems to have him primed to make the playoff roster, though there are obvious questions about whether they can trust that small sample size of effectiveness when the stakes are highest.

Thus, you don’t want to look at the raw results to determine if Diaz’s improvement is real or not, but rather whether the stuff is actually better and whether the arm angle issue he himself identified as a problem is on the path to correction or not.

“I think with a good arm angle, my fastball run way better than how I’m throwing right now,” he said. “I’m throwing the ball side to side, so my slider is getting flat in the middle. My fastball is running through the bat, so that’s why we are working now on that, get my arm angle back, and try to keep going and keep working.”

Well, good news, it does indeed seem like everything is trending int he right direction.

The velocity is up a tick on both primary pitches, and both the shape and location of the pitches are vastly improved, leading to the hitter seeing a package that’s something like 40% better than it was before.

Even the slight arm angle correction in the table is somewhat misleading, as things have only improved as time went on.

So to answer whether there’s real improvement behind Diaz’s September performance, well it’s a resounding yes, and there’s at least some hope that he’s rounding into form at the perfect time for the Dodgers.

That said — and you knew this was coming — it’s difficult to ever rely on five innings to get a read on anything. Relivers are volatile, the playoffs are volatile, and Diaz himself has been almost comically volatile in just this year alone. Things could very easily regress just as quickly as they’ve improved. However, if his September outings are all you have to go on, then combined with his elite history of production, it sure seems like Edwin Diaz and his upside could at least warrant a shot on the playoff roster.