Fantasy Baseball Waiver Wire: Quinn Priester's two-month surge makes him a must-roster pitcher, and more

Quinn Priester just keeps getting the job done. This time around, he limited the Mariners to just two runs over seven innings of work on Wednesday with six strikeouts to two walks. And, believe it or not, that objectively excellent performance actually slightly raised Priester's ERA since the start of June to 2.47, which highlights how good he's been in that stretch.

It's been nearly two months of a mid-2.00s ERA with 54 strikeouts to just 11 walks in 51 innings of work, which is pretty impressive. How's he doing it? Well, first off, it's worth noting that it hasn't come about alongside or as a result of a significant change in his approach. The groundwork for that was laid before the season when Priester added a cutter, changed his slider, stopped throwing his changeup as often, and ditched his four-seamer. Those changes have made his slider play up significantly better than it did last season, while the cutter has given him a better alternative to the four-seamer and changeup to handle lefties. 

What's the main difference between the past two months for Priester and the first month-plus? Well, he's gone from a really poor 4.2% K-BB% in April and May to a downright excellent 21.1% mark since. Because Priester already brings an elite groundball rate to the table, if he can truly be an above-average strikeout pitcher, the whole profile becomes a lot more interesting.

Is it sustainable? That's where I'm a bit more skeptical. Because it wasn't accompanied by a dramatic shift in either pitch usage or velocity, it mostly seems to come down to Priester pitching better. That's obvious, but it's worth saying: Priester hasn't necessarily totally remade himself mid-season, he's just pitching at a really high level right now. Which might not be as sustainable as if his turnaround had come with some big shift in his skill set.

That doesn't mean it isn't sustainable. Maybe it took a few months for those changes he made at the beginning of the season to lock in. That's a reasonable theory, for certain. But it does make me slightly wary of fully buying into the breakout here. I like what Priester is doing, certainly, but I'm not necessarily ready to declare he's a must-start pitcher, or anything.

But must-roster? Yeah, given how good he's been over the past two months, I can get on board with that. His play demands it at this point. 

Here's what else you need to know about from Wednesday's action around MLB: 

Thursday's waiver-wire targets

Brandon Walter, SP, Astros (46%) – Walter kind of came out of nowhere as a 28-year-old rookie with no real prospect pedigree to speak of, but I really like what he's done so far. He doesn't throw hard, but he locates his four-seamer well and mixes his pitches consistently enough that his 91-92 mph "heater" actually has a whiff rate over 30%, with excellent quality of contact metrics, too. And his changeup has been even better, looking like a legitimate weapon (he got four of his swings and misses with it Wednesday against the Diamondbacks). The rest of the arsenal is just okay in terms of stuff, but Walter's command has just been incredible, made even more impressive by the fact that he missed all of last season with a shoulder injury. Walter limited the Diamondbacks to one run over seven innings for his third straight quality start and sixth in his past eight tries, and now has a 3.35 ERA on the season with 52 strikeouts to just four walks in 53.2 innings of work. I don't fully buy into this being sustainable, but he's making it work right now, and he gets the Nationals and Red Sox in a two-start week next week, making him a viable streamer at the least. 

Royce Lewis, 3B, Twins (71%) – I think we're seeing Lewis start to figure it out again. At least, I hope so. Lewis went 2 for 2 with a homer and a walk, his third multi-hit game in four tries and his third homer in that same span. It's a small sample size, but then, everything with Lewis is a small sample size, including his slumps. But the key thing to keep in mind here is that despite his poor production over the past year or so, Lewis' underlying numbers have remained strong, and he actually has a career-high .358 expected wOBA for the season now; and that's up to a .386 mark over his past 100 plate appearances. Lewis has been a must-start player before, and that makes it easy to buy in when he's showing that upside again, even in a small sample. 

Joe Boyle, SP, Rays (40%) – With Taj Bradley sent down to Triple-A, it would seemingly open up a rotation spot for Boyle, who has earned it. He's allowed just two earned runs in 16 innings in the majors so far this season, but it's his work down in Triple-A that really impresses – over 73 innings, he had a 1.85 ERA with a 33% strikeout rate and 10.6% walk rate. That's a high-ish walk rate but actually represents real improvement for Boyle, and is probably good enough given how dominant the stuff can be. There's always the concern that the Rays will have an especially quick hook with any pitcher, and Boyle is certainly no exception. But if he pitches to his potential, Boyle is talented enough to make that irrelevant. If you're looking for upside on the wire, he's got plenty of it. 

Matt Shaw, 3B, Cubs (47%) – I want to believe Shaw is starting to figure it out. I liked him as a prospect and hoped he would hit the ground running as a seemingly polished all-around contributor, so the fact that he has three of his five homers for the season in the past five games should be a big deal, right? Here's the problem: None of Shaw's homers has traveled over 400 feet so far or been hit harder than 102.6 mph. I know you don't get extra points for how hard or for you hit your homers, but it still says to me that Shaw isn't showing the kind of underlying pop that's going to make him an impact bat. His expected wOBA over the past 50 plate appearances is up, but a .332 mark representing your hottest stretch of the season isn't particularly inspiring. Shaw does have a good approach at the plate and has hit all of his homers to the pull side, which is how you would overcome middling raw power, and maybe he's figuring out how to do the Isaac Paredes trick. I'm willing to add him if I have a roster spot to play with, just in case this is for real, but I'd be lying if I said I was optimistic about that. 

Spencer Horwitz, 1B, Pirates (6%) – Horwitz was the Pirates' big offseason acquisition, but he needed wrist surgery before the season even began, and mostly just hasn't looked right. But that is starting to change, as he has strung together a few big games in a row, following up a pair of three-hit efforts with a grand slam Wednesday, his third homer of the season and first since June. There isn't much here to get excited about yet, but Horwitz did have a .790 OPS last season, so maybe this is the start of him getting back to that level. He probably doesn't need to be added in more than NL-only and maybe 15-team Roto leagues, but at least he's on the radar again. 

Jon Gray, SP, Rangers (5%) – This one is purely speculative, but  … what if this is the answer to the Rangers' ongoing bullpen issues? In fairness, Robert Garcia has provided a steady hand in the ninth-inning role as of late, but he has neither the strikeout upside nor the control (nor, really, the track record) to feel confident in him as a lock-down closer. Gray, obviously, has no experience as a high-leverage reliever, having spent his entire career as a starter. But I do think his stuff could play up in a big way in the bullpen if he's healthy, and I think there's a chance he could emerge as a really good reliever for the Rangers if they stick with him in the bullpen. You probably don't need to go add Gray right now – he pitched in the sixth, seventh, and eighth innings in his return from the IL Wednesday – but he's a name to keep an eye on over the next few weeks.