Zack Wheeler's return from a significant surgery last September has gone about as well as anyone could have asked for through three starts.
Well, unless you ask Wheeler himself.
"Just a little off," Wheeler said after last Wednesday's quality start against the A's.
To be clear, Wheeler has acknowledged that he's fully healthy and has expressed how grateful he is to be back on the mound, where he's racked up a 3.12 ERA through three starts. He's completed at least six innings in each of his past two starts, and opponents are hitting just .180 against him with a .561 OPS. Both of those marks would be career bests.
But, in typical Wheeler fashion, he's still looking for more as he works his way back toward being his Cy Young-caliber self.
With that in mind, here are four things to monitor when Wheeler takes the mound for Tuesday night's series opener against the Red Sox at Fenway Park.
1. Velocity
Wheeler's velocity has continued to improve as he ramps up, though there is still room for improvement.
His four-seam fastball averaged 95.0 mph his last time out. While it's not the 96.1 mph it averaged last season, it was his fastest in any of his three 2026 outings -- and a marked improvement from his five rehab starts in which his velo was down.
Most importantly, though, that's right in line with where his velo typically is at this point in his progression. Looking specifically at his third start of each season, Wheeler's four-seamer averaged 94.6 mph in 2025 and 93.9 mph in '24 -- both lower than last Wednesday's 95.0 mph.
But now, it will be important to monitor whether those velo readings continue to creep up as they would under normal circumstances.
After all, Wheeler's fastest pitch through three starts is 96.5 mph. Last season, he topped out at 98.8 mph and threw 224 pitches of at least 97 mph -- a number he hasn't hit to this point.
Of course, only four of those 224 pitches came within his first three starts of the season -- and all four were on Opening Day.
In other words, it's nothing to worry about ... yet.
2. Breaking balls
When Wheeler described feeling a bit off last week, he noted that applied "especially with the sweeper and curveball."
Well, the good news is both the movement and spin rates on those pitches are just as good -- if not a little better -- than past seasons. In other words, each pitch is doing exactly what it should be doing.
The one thing to watch against Boston will be how much swing-and-miss Wheeler generates with his breaking ball, especially his curve.
Though it's not a frequently used pitch by any means, Wheeler's curve is a legitimate weapon against left-handed hitters. Last season, it generated a whiff rate of 55.3% -- the second highest among 111 pitchers to throw at least 200 curveballs.
Albeit an incredibly small sample, opposing hitters have whiffed on just four of their 14 swings (28.6%) against his curveball this year.
The main reason for that? Well ...
3. Command
One of the many things that has made Wheeler arguably the best pitcher in the Majors over the past half-decade is his pinpoint command.
In his first three starts, however, that hasn't quite been there.
It's not that Wheeler's pitches are all over the place or he's walking a ton of guys -- though his walk rate is a bit elevated -- it's that he's just not hitting all of his spots. Take, for instance, the RBI single he allowed to Jacob Wilson on this two-strike pitch last Wednesday:
Though it's clearly outside the zone, Wilson was able to reach enough of it to poke the ball into right field for a run-scoring hit. Ideally, Wheeler said, that 1-2 pitch would have been in a spot that made it unhittable.
"That sweeper needs to be off the plate for a chase instead of just, you know, the outer edge," Wheeler said.
There's also a matter of just throwing more strikes, in general.
Overall, Wheeler has thrown just 39.9% of his pitches in the zone. That's the fifth-lowest rate among 315 pitchers with at least 15 innings this season. That's contributed to an 8.8% walk rate, which would be his highest since 2017 -- his first season back after missing two full seasons due to Tommy John surgery and another subsequent elbow surgery during his rehab.
4. Feel
This one isn't really something you can monitor during Tuesday's game itself, but given what Wheeler said after his last start, it'll be interesting to hear what he has to say after facing the Red Sox.
"Mostly it's just how I feel honestly, rather than anything results-wise," Wheeler said last week. "It's just a tick off still. It's kind of something as simple as getting through the ball and driving the ball toward home, instead of kind of just throwing it and falling off.
"So I'll try to kind of nail that down in my next bullpen and just finish my pitches a little bit more, rather than just kind of throwing."
All eyes (and ears) will be on Wheeler come Tuesday night.