On July 18th, the New York Yankees made a blockbuster trade with the Chicago White Sox. The headline from The New York Times read: "Yankees Acquire Todd Frazier and David Robertson in Trade With White Sox". Perhaps the most important piece of the Yankees half of the deal wasn't mentioned in the headline at all.

That piece is twenty-eight-year-old right-handed reliever Tommy Kahnle. On paper, Kahnle is a secondary piece, behind Aroldis Chapman, Dellin Betances, and David Robertson in what is now the newest version of the Yankees' super-bullpen.

Kahnle lacks the name-brand recognition of Chapman, Betances, and Robertson, but so far in 2017, he has been considerably better than all three.

He has been the ninth-most valuable reliever in the league at 1.8 fWAR, 0.3 fWAR above the Yankees' next most valuable reliever Chad Green. Kahnle has been the 9th-best reliever in the league over just 46 innings; of the eight above him on the WAR leaderboard, all but one (Trevor Rosenthal) have over 50 innings pitched.

in 129 1⁄ 3 innings pitched prior to this season, Kahnle had been worth exactly zero wins above replacement. He had a career earned run average of 4.04 and a fielding independent pitched of 4.23, hardly encouraging numbers for a late-twenties middle relief pitcher.

Kahnle's struggles were caused by his control problems. Prior to 2017, his walk rate was 14.1 percent. He walked 5.5 batters per nine innings. Even though he had a hard time throwing strikes, the strikeouts were still there. He has never had a season in which he struck out less than 8 batters per nine innings, and his career strikeout rate prior to this year was a respectable 22.7 percent.

This year, everything has changed in a big way. Kahnle is throwing the ball in the zone, getting batters to chase, and missing more bats than ever, a lethal combination. As a result, his walk rate is at career-best levels. He has walked just 4.8 percent of batters and just 1.72 batters per nine innings.

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His zone percentage has improved slightly, from 50.9 percent in 2016 to a career-best 53 percent this year, but the real difference has come in his chase and swinging strike rate.

Batters are making contact on his pitches just 69.6 percent of the time, and just 76.7 percent of the time on pitches in the strike zone, good for 16th-best among relievers. Batters have swung at his pitches 54 percent of the time, 11th-most in the league, and at the same time he has one of the best swinging strike rates in the league. His swinging strike rate is 16.5 percent, also 11th-highest in the league.

Kahnle makes his living with a three pitch mix: a four-seam fastball, a changeup, and a slider. He uses his fastball around 70 percent of time, with the other two pitches varyingly making up the other 30 percent. He is throwing all three of his pitches harder than ever.

His fastball is now one of the fastest pitches in the league, averaging 98.39 miles per hour according to Brooks Baseball. He throws a hard changeup just under 91 miles per hour, and his slider a little softer at about 87 miles per hour.

He has used his newfound control and velocity to become one of the premier strikeout relievers in the game. He has struck out 14.36 batters per nine innings in 2017, fourth-best among relievers behind Craig Kimbrel, Betances, and Corey Knebel. His K/BB ratio is fifth-best in the league at 8.22. His abnormally high .340 batting average on balls in play has had little effect on him, due to his high number of strikeouts and low number of walks.

Just going by this year’s numbers, Kahnle has been the Yankees best reliever. He has the strikeouts of Betances and Chapman without the high walk numbers. Although it is almost impossible to imagine Kahnle stealing the closer role from the struggling Chapman and the other, more established names in the Yankees' bullpen, it is easier to see him getting a bigger role if he stays on this dominant pace.

Look for Tommy Kahnle to be this years unheralded star coming out of the bullpen in October should the Yankees make a deep run in the postseason.

Dylan Svoboda is a writer for Beyond The Box Score and BP Milwaukee. You can follow him on Twitter at @svodylan.