A month and a half of baseball is in the books, and Jason Vargas leads the majors in ERA.

That’s weird, man.

The Kansas City southpaw, who threw seven shutout innings last Thursday, now owns a 1.01 ERA in 44 â…” innings, after coming into the season with a lifetime 4.18 ERA over more than 1,200 career frames. He's only allowed one home run this season, despite a 42.0% ground-ball rate, while his strand rate is above 87.0%.

But the veteran is more interesting than your basic star of Small Sample Size Theater (that's a thing, right?), as there are indicators Vargas can be an above-average starter going forward. He's striking out more batters than he ever has in his career while walking fewer, and the result is a 18.2% K-BB rate, which is tied for 18th in MLB.

This marks a continuation of a run that began last September, when Vargas returned from Tommy John surgery and posted a 17.0% K-BB rate in three starts.

While his 39.7% ground-ball rate does leave him exposed to the long ball, his xFIP is still just 3.72. After adjusting for league and park effects, this is 10% better than league average and tied for 33rd best among the 99 qualified starting pitchers in the game.

More Whiffs

Vargas is getting more swings and misses than he ever has in his career, and it's not close. He's generating a whiff on 12.5% of his pitches, marking a 4.1% improvement over his career average, per FanGraphs.

His changeup has always been his best swing-and-miss pitch, and this is again the case this year. For his career, Vargas’ changeup has generated an 18.6% swinging-strike rate and this season, that number is up to 25.8%, per PITCHf/x data at FanGraphs.

Even if the pitch regresses towards his career average -- which is possible, since its vertical and horizontal movement is relatively unchanged -- this should be more than adequate. His whiff per swing rate on the pitch ranks 39th among the 255 pitchers who have thrown at least 500 changeups since 2007.

Vargas getting misses against his changeup is hardly news -- it's been his best pitch for the entirety of his career. What's more surprising is the fact that his fastball is also generating more whiffs...yes, you read that correctly.

Since 2007, his average fastball velocity has been around 88 miles per hour, and until last season, his fastball whiff rate never cleared 5.9%, according to Brooks Baseball. By 2014, the pitch’s whiff rate was around 3.0% before plummeting to 1.03% in 2015 in the months preceding his surgery (the average whiff rate for a four-seamer is about 7.0%).

Since his return, though, this rate is up to 7.3% and is at 6.6% so far this year. Remove last year's three starts from the equation, and this would mark a new career high, despite the fact that Vargas is only throwing the pitch at 86.9 miles per hour, which ranks 76th out of the 77 pitchers who have thrown at least 200 four-seamers this season.

Among this group, his fastball's whiff per swing rate ranks 29th. In this case, increased horizontal movement does seem to be the driving force, as the pitch is moving in on righties more than it ever has.

This is a new development for Vargas, who used to work predominantly in the outer part of the zone against righties with his fastball, and this is something Paul Sporer noted for FanGraphs earlier in the season. Take a look at Vargas’ fastball heat map from 2007 to 2015.

And now, contrast it with the map since last September.

Opposite-handed hitters are having a hard time against the pitch, posting an 8.2% whiff rate against Vargas’ fastball this season and a 7.3% rate since last September. From 2007 through 2015, righties had just a 4.4% swinging-strike rate against the pitch (against lefties, the fastball’s whiff rate has stayed consistently low).

This data lends credence to the idea that Vargas’ increased strikeout rate is more than just a sample size fluke, while his best zone percentage in a decade helps explain the low walk rate. As for the third FIP component, an unsustainably low 2.0% home-run-per-fly-ball rate has been his best friend here, and regression in this department will probably be his biggest foe going forward.

Then again, Vargas may be able to fight this off, since he's allowed a lower than average rate here for much of his career (it should also be noted that Vargas’ Statcast-based expected wOBA is just .249, suggesting weak contact has also played a role in his early success). And even if the homer rate does regress to the league mean, if he sustains those strong strikeout and walk rates, good results should still follow.

At least some regression across the board is probably coming, but it's worth noting the projection models are already buying in. Vargas was forecasted to pitch to a 4.22 ERA by ZiPS and a 4.44 ERA by Steamer before the season. From now until the end of the year, ZiPS and Steamer say Vargas will post ERAs of 3.64 and 4.16, respectively.

His stay atop the ERA leaderboard probably won't last much longer, but Vargas seems to have made real improvements and could be an above-average starter going forward.