Zach Britton kept the ball on the ground at a historic rate for the Orioles this year

Zach Britton followed his surprisingly good 2014 with a perhaps-less-surprisingly good 2015. If you go by fWAR, Britton notched the fourth-highest total in the game, and he was mere decimal points behind third place Dellin Betances. By rWAR, he drops to only eighth place. This success should net him a huge payday, as MLB Trade Rumors predicts he will earn $6.9 million in his second trip through salary arbitration, more than double the $3.2 million he earned in 2015.

This year Britton improved nearly every facet of his game. Strikeouts? Up. Ground balls? Up. Fastball velocity? Up. Walks? Down. As a result, his FIP and xFIP dropped precipitously.

But something got lost in the shuffle. Something Britton did that no one else has done in at least the past 13 years in 1,405 pitcher-seasons of relief.

To start with, he and his flaming two-seam fastball just notched the second-lowest flyball rate of any reliever since 2002. Here are the top ten seasons in that timeframe, ordered by fewest fly balls per batter faced:

Being on this list is pretty special. Being on it twice is even more special. After all, Brad Ziegler has made a good career for himself. At age 36 he just had a team option exercised that will pay him $5.5 million next year.

Now let’s add one more bit of information. We know that outside of a ground ball, the best thing a pitcher can do is strike a batter out. It turns out that Britton’s 2015 season was special in this regard as well. Here is the above table but with strikeout rate added:

While several relievers on this list can boast high strikeout rates, none can touch Britton's 31.23% rate he notched this year. In fact, since 2002, no reliever with a strikeout rate equal to or higher than Britton’s rate has a flyball rate below 10.2%.

To see just how special Britton’s 2015 season was, I combined strikeouts and flyballs into a strikeout-per-flyball rate stat:

Before this year, Eric Gagne’s Cy Young award-winning 2003 season stood atop the list. In second place was Craig Kimbrel’s record-setting 50.2% strikeout rate in 2012. Britton’s 2015 destroyed them both.

Britton’s 2014 season came close to matching these two pound-for-pound. So did Andrew Miller’s amazing run. And this year, Seattle’s Carson Smith put up a great season himself, burning lots of worms while getting lots of swings and misses. The Yankees’ Dellin Betances also had a great 2015.

But Britton’s 2015 season beat them all by a considerable margin. By how much? Take a look at where Britton’s season falls with respect to those who came before him:

You can’t read the names, but aside from Gagne and Britton, they’re not that important. You can see how far above the rest of the pack Britton is. That success will factor into the raise he'll get this offseason.