If you’ve spent anytime looking at Baseball Prospectus new pitching metric Deserved Run Average (DRA) leader board, it can give you a pretty solid indication of a pitchers performance compared to the rest of the league. It should come as no surprise, given all of the factors that DRA takes into account, that Dellin Betances grades out as the top relief pitcher in baseball so far this season. The mammoth Yankee setup man has racked up 49 strikeouts in just 29 innings, while surrendering just three un-earned runs in 26 appearances this season. He’s also coming off a stretch in which he set down 29 consecutive batters before allowing a hit.

It may come as a shock to most fantasy owners that the second-best reliever in baseball this season, according to DRA, is Will Harris of the Houston Astros. Some (if not most) fantasy owners might not even know who he is right now. That’s okay, because frankly nobody could have seen him coming. If you were tasked with the job of choosing a single player as the potential symbol of the Astros remarkable turnaround prior to this season, Harris might be the last guy you would choose. On a team stocked with young talent and an extreme emphasis on advanced analytics, a nondescript journeyman middle reliever has suddenly evolved into one of its most valuable core pieces. Go figure.

In Harris’ previous stops in Arizona and Colorado over the last three years, he posted ERA’s of 4.34, 2.91 and 8.15, respectively. There is nothing in either his stat line or scouting report that would suggest a potential budding superstar coming into the current campaign. Everything about his profile would lead you to believe that he’s a 30-year old, two-pitch (cutter and curveball) middle reliever, capable of eating low leverage innings at the Major League level.

It doesn’t make any sense that Harris could evolve into the games second-best reliever, statistically speaking, overnight. Harris leads the majors in both opponents’ batting average (.073) and WHIP (0.47), while ranking second in ERA (0.35) among pitchers with at least 20 innings of work this season. Just like any good mystery, the answer isn’t obvious, you have to do a little digging to unearth the truth about the transformation.

The first place you always look is in the velocity department. It’s fairly simple, but the harder a pitcher is throwing, the less time hitters have to react. It’s not uncommon for a reliever (think Wade Davis) to see an uptick in velocity, which results in a performance boost. However, that doesn’t appear to be the case with Harris this season according to the PITCHf/x data available on Brooks Baseball.

Harris has always been a strikeout machine throughout his career. He’s fanned more than a batter per inning in each of the last four seasons, posting a career-high 10.87 K/9 mark this season. He ranks inside the top 10 in strikeouts among relief pitchers exclusively, with 31 punch-outs in 25 and two-thirds innings of work, this season.

The biggest change for Harris has been the substantial rise in his ground-ball rate, which has climbed into elite territory (54.9%) this year. You’re not going to mistake him for Zach Britton, the undisputed king of ground-ball relievers, but it’s worth noting that he’s evolved from a pitcher who failed to post a ground-ball rate above 37 percent in two of the last three seasons to one of the games premier worm killers.

Sure, you can write it off as a pitcher getting extremely “lucky” when you stare at Harris’ completely unsustainable .100 BABIP this season. There is some regression coming, no doubt, but you have to look at that number in context with the rest of his profile.

The intoxicating combination of strikeouts and ground balls means that even when hitters manage to put the bat on the ball against Harris, it’s resulting in weak contact and a plethora of easy outs this season. According to the batted ball data on FanGraphs, provided by Baseball Info Solutions, Harris is running a 21.6% hard contact rate this season, a nearly 10% drop from his career rate, which was 30.2% coming into the year.

From a purely statistical standpoint, Harris is enjoying the best season of his career generating strikeouts and ground balls at elite rates. So far, we’ve already ruled out increased velocity as the main contributor. How about pitch selection? Well on the surface it would appear as though nothing has substantially changed for Harris, who is actually relying more on his cutter this season than he has in the past.

Here is where the fun begins. Basically nobody is hitting Harris’ cutter this year. Opponents are batting a microscopic .067 against the offering. If that sounds like a dramatic improvement from previous years, here is what it looks like visually.

To put it in perspective, once PITCHf/x cameras were installed in 2007-08, opponents batted just .200 off Mariano Rivera’s fabled cutter. If you’re thinking that these results are the by-product of him pitching in low-leverage situations, Harris has you there as well. On Monday night, Harris entered the game with the Astros trailing 2-1, with runners on second and third with only one out. He proceeded to strike out Steve Pearce and get Caleb Joseph to fly out to end the threat. Harris worked a scoreless one, two, three frame the following inning as Houston came back to win the game.

According to Owen Watson of FanGraphs, Harris’ “hard cutter/curveball combination has been very effective in two parts of the strike zone: 10 out of his 13 strikeouts with the cutter have been in the upper half of the strike zone and above, while all but one of his 11 strikeouts with his curveball have been in the lower half of the zone and below.”

Simply put, there doesn’t appear to be anything inherently fluky about Harris’ stellar performance thus far. Using the DRA leader board to uncover hidden gems that other owners in your league may be overlooking like Harris, Michael Blazek, Alex Wilson and Carlos Villanueva just to name a few, is a strategy that can pay off for owners in deeper formats where anyone with a live arm is worth rostering.

Banking on Harris continuing to pitch at this elite of a level seems like a risky proposition, but it’s clear that he’s a reliever fantasy owners, especially those in deeper dynasty formats, need to have not only on their radar, but on their rosters as well.

George Bissell also writes for Baseball Prospectus. You can follow him on Twitter @GeorgeBissell