The Mets have two of baseball's very best at limiting power output from opposing hitters. Isolated power—ISO, for short—is a statistic that measures extra-base hits per at-bat. It is calculated by subtracting batting average from slugging percentage. For example, Yoenis Cespedes has a .611 slugging percentage and a .281 batting average, which gives him a .330 ISO, an elite number. Major league average isolated power this season is .157.
By looking at ISO allowed by starting pitchers, we can get a measure of how often a starting pitcher is giving up extra-base hits. A starting pitcher who limits power output from opponents helps put himself in a better position to prevent runs than one who doesn't. ISO against can also give a look at how difficult a pitcher is to square up and hit well, because extra-base hits usually fit that description.
Among starting pitchers who have thrown at least 500 pitches this year, Noah Syndergaard and Steven Matz make up two of the top three in ISO against, ranked in an ascending order from lowest ISO against to highest. Matz has the second-best ISO against in baseball at .061, while Syndergaard is third-best at .070. For some perspective, light-hitting Eric Campbell has a career ISO in the big leagues of .092. Matz and Syndergaard have essentially turned all of their opponents into lighter-hitting versions of Eric Campbell.
Matz and Syndergaard are ranked ahead of notable aces like Jake Arrieta (.071), Clayton Kershaw (.079), Chris Sale (.095), Stephen Strasburg (.103) and Jose Fernandez (.103). Their seasons to this point are reminiscent of Matt Harvey's peak 2013 season, during which he limited opponents to a .073 ISO.
A large part of the reason why Matz and Syndergaard are so difficult to hit for power against is that they combine a top-notch pitch mix with command. Syndergaard's stuff is more overpowering, as it's the best pure stuff in the game right now—and probably the best in recent memory. Matz gets more deception in his delivery. Batters don't see the ball well out of his hand and pick it up late, often leading to defensive swings.
They also register a lot of ground balls. Matz's ground ball rate sits at 55.6%, with Syndergaard's at 57.0%, both well above the major league average of 45%. Ground balls don't usually go for extra-base hits unless they're hit directly down the lines. The major league average ISO against for ground balls is just .020.
Here's how the rest of the Mets' starting pitching staff ranks in ISO against among the 146 major league starting pitchers who have thrown at least 500 pitches in 2016:
Keep in mind that the major league average ISO against is .157, and the National League average is .153. To have four out of five starting pitchers pitching to a well-above-average ISO against is an impressive accomplishment.