Hey guys, Jon Lester is not the "ace" of the Chicago Cubs.

That distinction now belongs to Jake Arrieta, who is having yet another brilliant season with the Cubbies. In 23 starts (155 1/3 innings) he is 13-6 with a 2.38 ERA and a 2.65 Fielding Independent Pitching (FIP). He leads all Cubs pitchers with a http://t.co/CqXAGPwTpt pic.twitter.com/Etg29aCC1m

— Baseball Reference (@baseball_ref) August 9, 2015

And yet, he's rarely in the conversation of the best pitchers in Major League Baseball.

What makes the right-hander really special is his dominance against left-handed hitters, who are hitting just .177/.251/.271 against him this year, as opposed to righties who are hitting a barely-better .228/.273/.352. He's striking out left-handers at a better rate than right-handers (10.01 vs. 8.43 K/9) and has given up fewer homers to them as well.

His repretoire has simply improved drastically since he came to Chicago last year. His fastball consistently sits between 94 and 96 mph and he rarely leaves it out over the plate, showing impeccable control and location. His cutter bears in on left-handers and away from righties, inducing ground balls and weak contact from both. He has a curveball that, when it's on, is a swing-and-miss pitch to hitters on both sides of the plate, as well as a seldom-used change-up that can be an effective strikeout pitch against lefties.

He has a complete arsenal and he uses it effectively. According to Fangraphs, just 21.3% of all balls put in play against him this season have been "hard hit," 11th-best in the Majors. 

But it was not always so. Before coming to Chicago, Arrieta's secondary pitch was a slider that was a few miles per hour slower than the cutter he throws now. After coming to the Cubs, Arrieta abandoned the slider in exchange for the cutter, and since then, has pitched far more effectively with the added velocity.

Certainly, Max Scherzer, Clayton Kershaw and Zack Greinke are leading contenders for the NL Cy Young Award, and it's going to be very difficult to knock them off the top of the perch. 

But make no mistake, Jake Arrieta is one of the five best pitchers in the National League right now, and he's the best starter on a Chicago Cubs team that is making a hard push for the playoffs.