Steven Matz‘s lengthy injury history has not only left questions about his durability but finds the talented southpaw struggling to find his groove with the New York Mets. 

Opening Day was supposed to be the first time the New York Mets would have all five of their big-time starters healthy and ready to take the National League by storm.

Instead, Steven Matz was shut down with elbow issues before the season began, and it wasn’t until recently that the 26-year-old returned to action.

While Matz’s numbers are solid—he’s gone 1-1 with a 3.60 ERA and 1.10 WHIP over three starts—something is missing this time around. He doesn’t look like the same pitcher.

Throughout his short career, Matz has gotten more effective as he worked deeper into games. This season, he’s been terrific the first time he works through the opposition’s lineup, but struggled the second-and-third time he faces the same batters in a game.

Where’s the Slider?

Due to his past elbow issues, he has gotten away from throwing his slider this season. This not only means that he has lost one of his better pitches; it has also impacted the effectiveness of his other offerings and, as a result, his overall effectiveness.

In 2016, Matz threw his slider only 10.4 percent of the time, yet it was one of his best pitches. His slider, which sat around 90 mph, was a legitimate out pitch, producing a .230 BAA (batting average against) and 21.9 strikeout percentage.

Without the slider in his repertoire, Matz’s K/9 rate has fallen to 6.3 this season, down from his from 8.47 career mark. He’s also seen a drop in his groundball rate, from 51.1 percent in 2016 to 44.3 percent this season.

Trouble With the Curve

Having all but abandoned his slider, Matz’s curveball has seen an increase in usage, from 16.4 percent in 2016 to more than 23 percent in 2017.

Opposing batters have either gotten used to the pitch or know when it’s coming, as they’re hitting a robust .313 with a .875 OPS against it this season. Those numbers are superior to the .237 BA and .559 OPS his curve limited batters to a year ago.

Without a fourth weapon in his arsenal, Matz’s other offerings have seen a regression, specifically his curveball. In 2016, Matz only had to use on curveball 16.4 percent of the time, but this year that number has increased to 23 percent.

Perhaps the most troubling of all is that the opposition is making far more solid contact with the pitch than they used to, with 16 percent more line drives coming against what used to be a wipeout offering.

Regression is Coming

While the usual statistics say that Matz has been solid, there’s a legitimate argument to be made that he’s been lucky, not good.

So far in 2017, he has stranded 93.3 percent of runners on base. That’s very high and likely to regress to the mean as the season continues. Another bad sign: His FIP of 5.89 is more than two full runs above his ERA of 3.60.

Maybe Matz needs more time to learn how to pitch without his slider, or maybe he will begin to use the pitch again when his elbow feels better, laying off his curveball usage.

Either way, without his full arsenal, Matz is no longer the pitcher he used to be.