Mets playoffs: Cubs ace Jake Arrieta came out of nowhere

Jake Arrieta wasn't exactly a household name before last season. Traded to the Cubs by the Orioles during the 2013 season, Arrieta was one of just two Orioles mentioned in the episode of Veep that featured Camden Yards and some Orioles players the year before. I've seen every episode of that show and remember that episode pretty clearly because Camden Yards is pretty great. But until being reminded very recently, I had no clue that I had seen Arrieta and heard Vice President Selina Meyer, played by Julia Louis-Dreyfus, mention him by name.

The point here is that Arrieta was eminently forgettable at the time—which is understandable. He had entered the 2013 season with a 5.33 ERA in 334.1 innings of major league work, and things weren't going any better that season. Arrieta had a 7.23 ERA in five major league starts with the Orioles and pitched more in the minors than he did in the majors. and even after he was traded to the Cubs on July 2, he split his time between Triple-A and the Cubs' roster, though he had a 3.66 ERA with Chicago in nine starts.

Even last year, Arrieta didn't make his first major league start until May 3. Since then, though, he has been outstanding. In 58 starts for the Cubs since, he has a 2.08 ERA and 2.31 FIP. He has quite understandably not been back to the minors.

Pretty much everything has changed drastically for Arrieta. Before last year, his strikeout and walk rates were mediocre, and he gave up more than a home run per nine innings. Since coming up to the Cubs last year, his strikeout and walk rates have been excellent—9.40 and 2.08 per nine, respectively—and he's allowed just 0.35 home runs per nine. And with a 1.77 ERA and 2.35 FIP this year in 33 starts, he's a Cy Young contender, right up there with Zack Greinke and Clayton Kershaw.

On top of the strikeout, walk, and home run rates, Arrieta has also gotten ground balls much more often over the past two seasons than he had before. And he's been pretty great with runners on base, stranding 80 percent of baserunners this year, the fourth-highest rate among qualified starters in the game. What the hell happened?

Beyond the Box Score took a look at Arrieta's complete turnaround following the 2014 season and noted that his slider usage went way up. That remained the case this year, as he threw the pitch 29.6 percent of the time, according to Brooks Baseball. Arrieta significantly reduced his use of a four-seam fastball, instead throwing a two-seam as his most frequent offering.

He also changed the way he attacked opposing hitters, and he essentially figured out how to command his pitches. Mike Petriello broke down Arrieta's pitches in late June this year, pointing out that while he's capable of throwing hard, his four-seam fastball was just never that good—but his other pitches certainly are.

Per Brooks, his two-seam fastball averages 95.3 miles per hour, his changeup 89.7 miles per hour, his slider 90.7 miles per hour and his curve 81.2 miles per hour. The four-seam fastball that he rarely uses average 95 miles per hour. The fastballs don't get many swings-and-misses, but the offspeed stuff sure does. His change gets whiffs 15 percent of the time, and his slider and curve get them 17 percent of the time. Those are all above-average swinging strike rates.

The Cardinals touched up Arrieta a bit in the NLDS, which is perhaps encouraging for the Mets. They'll pitch Noah Syndergaard in Game 2, which should make for another great night of pitching in a playoff run that has thus far featured a whole lot of it. But if Jake Arrieta makes an appearance on one of my favorite shows in the future, I'm going to guess I won't forget that he did.