Jason Vargas is Death To Rolling Things

The Giants are not exactly one of the tougher matchups for a pitcher, and especially not for a lefty, as they rank dead last in wOBA against southpaws. Even so, I did not see Jason Vargas tossing a complete-game shutout against them on Wednesday night.

Given the lack of resistance we have come to expect from the Giants’ lineup, that start alone probably would not have made me take notice of Vargas as a fantasy option going forward. Wednesday’s outing in combination with his previous start — a seven-inning, one-run affair on the road against the Dodgers — does give me reason to pause. Looking even further back, Vargas had been effective over a five-start run that was interrupted by an IL stint for a strained hamstring. During that stretch, he posted a 2.74 ERA and a 1.22 WHIP, and though he did not last more than 5.1 innings in any of those starts, he recorded three game scores above 50 and never fell below a 45 game score.

Because of his recent consistency, Vargas has been able to overcome a miserable beginning to his 2019 season. After 10 appearances (nine starts) and 45.1 innings, he has a 3.57 ERA and a 1.35 WHIP. The latter mark is not especially impressive, but given that Vargas has a 9.8 percent walk rate, it’s something of an accomplishment that he is only two points behind the major league average for WHIP. He appears due for some ERA regression, thanks to an 80.0 percent strand rate, and skeptics can also point to his .280 BABIP. Yet xBA says his .247 batting average allowed is exactly what it should be, and xwOBA pegs his current .319 wOBA as being only nine points too low.

Those measures don’t make Vargas out to be a world-beater, but they do suggest that he has pitched well enough to have the same batting average against as Masahiro Tanaka and Jose Berrios and a wOBA in the same neighborhood as Eduardo Rodriguez‘s and Tyler Mahle’s. It has helped Vargas that he has a pitcher-friendly home venue, but he has helped himself by inducing the most harmless types of ground ball contact possible. He doesn’t always get a lot of grounders, but when he does, they’re some of the least interesting grounders in the world.

Specifically, Vargas is one of a small group of pitchers who has excelled at getting grounders that are weakly hit and at getting batters to pull their grounders. So far this season, exit velocity on ground balls (EV GB) is positively correlated with ground ball batting average and ground ball pull rate is negatively correlated with ground ball batting average (both at p < .02, min. 50 ground balls and 100 batted balls). The former relationship reinforces the correlation already established between GB EV and overall BABIP. The graph below shows the relationship between Avg on ground balls and GB EV, and ground ball pull rate has been color-coded. You can see that Vargas has been among the best pitchers in terms of both GB EV (79.7 mph) and ground ball pull rate (72.7 percent), and it has helped him to limit opponents to a .182 Avg on grounders.

The combination of low exit velocities and high pull rates on grounders doesn’t guarantee a low batting average, but in addition to the general trend depicted in the regression line, the concentrations of the highest pull rates below the line and the lowest pull rates above the line are noticeable. The only pitchers besides Vargas who have a GB EV below 83 mph and a ground ball pull rate above 68 percent are Justin Verlander and Dylan Bundy, who have respectively limited opponents to ground ball batting averages of .110 and .108.

Both Verlander and Bundy are far below the regression line, so both could be due to allow a higher rate of ground ball base hits. It hardly matters, as neither allows much contact in general. Vargas, who is getting swinging strikes at a puny 7.4 percent rate, almost certainly needs to keep inducing weak, pulled grounders to succeed at or near his current level. It’s not clear how Vargas has been doing this, but it doesn’t appear to be a fluke. Opponents mustered an even lower EV GB against Vargas last season, averaging 78.6 mph over a total of 120 ground balls. It didn’t show up in his stat line, as Vargas allowed a .278 Avg on grounders and a .276 Avg overall, but his xBA was a more modest .255.

The part of this trend that looks a little suspicious is the high pull rate. Vargas tends to pitch away from righties, and in 2018, hitters pulled grounders against him at a closer-to-normal 59.3 percent rate. Then again, his consistent ability to induce weak ground ball contact will probably be enough to allow him to prevent hits on balls in play and keep his ERA and WHIP at respectable levels.

None of this means that Vargas needs to be owned outside of deeper leagues, but he is barely being rostered in mixed leagues at all. With the Yankees, Cardinals, Braves and Phillies falling in line with Vargas’ projected upcoming start dates, there isn’t much urgency to add him right now. If he continues to succeed over his next couple of starts, that will be the time to add and stash him. The Mets’ schedule gets considerably easier after the All-Star break.

Statistical credits: FanGraphs, Baseball Savant.