BUFFALO, N.Y. -- It’s been a season of extremes for Steven Matz, the tantalizing left-hander who’s become impossible to predict.

When Matz is good, he’s great. Coming out of a strong camp, Matz opened the season 4-0 with a 2.31 ERA and looked like an early answer to the Blue Jays’ No. 2 rotation spot. Since then, though, the highs have matched the lows without much in-between. Matz now owns a 4.50 ERA after Sunday’s 6-3 loss to the Astros at Sahlen Field, but he’s still looking for that stretch of steady outings that represents his “normal.”

Matz’s stuff is there. That’s never been the question, and when you watch him pitch, it’s easy to see why he was one of baseball’s top-ranked pitching prospects prior to his debut with the Mets in 2015. As the 30-year-old allowed four runs on eight hits over 4 1/3 innings to the Astros Sunday, his fastball was flirting with 97 mph. The second home run Matz allowed came on a hanging slider, but the first, to Jose Altuve, came on a fastball that painted the inside edge.

“I feel like I had my really good fastball working, but the offspeed just wasn’t there,” Matz said. “It wasn’t crisp today. That’s unfortunate, because when you’ve got a really good fastball and you’ve got that fastball going, it makes all of the other stuff. The other stuff just wasn’t crisp. That’s what it boiled down to.”

Manager Charlie Montoyo said that it boiled down to that one word, too, “crisp.” That’s because, when Matz is off, it’s not usually that glaring.

Matz isn’t losing the zone entirely, walking the entire lineup or getting run out of the game in the first inning. He’s found ways to work consistently into the middle innings, now going five or more innings in 10 of his 12 starts this season, and while issues with walks or home runs have popped up once or twice, by no means are they flaws that follow him from start to start.

With that in mind, Matz’s approach leading into his next start is simple.

“Staying after it. That’s the biggest thing, not panicking too much,” Matz explained. “Honestly, looking at this [game], a couple of things here and there could have gone differently today. Balls just weren’t hit at guys today. Sometimes they’re hit right at guys. I’ll build off a good fastball, maybe work on my offspeed a bit between these starts, but keep going.”

Where Matz fits in this rotation long-term is important, too.

Early in the season, it looked like Matz could represent some upside in the top half of the rotation, but that role now belongs to Robbie Ray, the fellow lefty who has cut down his walks this year and become surprisingly consistent. Alek Manoah is set to make his third MLB start in Chicago this week and No. 1 prospect Nate Pearson is expected back at some point, both representing some upside as well, but this rotation needs a couple of rocks towards the back end to keep it steady. At least for now.

Matz has half of that equation handled, working deep into games and even reaching 112 pitches a couple of outings ago against the Yankees, when he struck out 10 batters over 6 2/3 innings of one-run ball in his best outing of the season. Some predictability from start to start is the next step, though, and while the lefty feels he’s close, he’ll need to begin establishing that next weekend in Boston.

Jansen exits early with hamstring injury

Catcher Danny Jansen was replaced midway through the game after he suffered a right hamstring strain. This came after he was thrown out on a fielder’s choice trying to advance from second to third, sliding to attempt to avoid the tag.

“He’s going to go get tests right now, and he’s also going to go get tests tomorrow to see how he’s doing,” said Montoyo.

Reese McGuire, who entered in Jansen’s place, has been seeing regular playing time recently, but with Alejandro Kirk still on the 60-day IL with a flexor strain, Triple-A catcher Riley Adams would likely be next in line. The club’s No. 18 prospect was called up briefly earlier this season, but didn’t see any game action. With the Triple-A Bisons, he’s opened the season hitting .250 with six home runs and a 1.010 OPS over 19 games.