DENVER -- The dirt path from the pitcher's mound to the home-plate area is a cool little touch at Chase Field. To Rockies right-hander Jon Gray, who will start tonight's National League Wild Card Game there, it seems a path to happiness.
Gray will face D-backs veteran ace Zack Greinke for the right to play the Dodgers in the NL Division Series presented by T-Mobile. While the D-backs earned home-field advantage by taking the top NL Wild Card berth, Gray feels at home at their home.
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In two starts at Arizona, Gray is 2-0 with a 2.77 ERA, with a whopping 20 strikeouts against one walk in 13 innings. Gray's slider -- his put-away pitch -- has been a key, and we'll get to some data on that in a bit. In Gray's mind, that quirky dirt path to the plate, he believes, has something to do with it. Somehow.
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"It might sound crazy, but I like the line -- the dirt path," Gray said. "It helps you line up. The mound feels good and tall, like you're going downhill. I just like it there.
"I think it helps my slider. I'm not sure [how]. It's all feel. That would be my guess."
Statcast™ science only goes so far. It's not going to unlock the physical, psychological, possibly mystic connection between the shaved patch of earth and the soul of Gray's slider.
But, hey, the numbers Statcast™ provides are pretty cool:
• Gray has racked up at least 13 swinging strikes in five of his 20 starts (he missed 2 1/2 months with a navicular stress fracture of his right foot). Two of those starts -- June 30, in his return from the injury, and Sept. 12 -- were at Chase Field. In those two games, 17 of the swinging strikes came on sliders. Here's a graphic presentation:

• In three total meetings, the D-backs are 4-for-29 (.138) with one extra-base hit and 17 strikeouts against Gray's slider. But the one hit went a long way -- a J.D. Martinez homer in Gray's loss at Coors Field on Sept. 2. The D-backs aren't much better against Gray's curve -- 3-for-15 (.200) with three doubles and five strikeouts. But Arizona has had success against his four-seam fastball -- 11-for-26 (.423) with two home runs and two doubles.
• How effective has Gray's slider been? Opponents have hit his slider with a 95-plus-mph exit velocity just 16.1 percent of the time. That ranks second among 88 starting pitchers with a minimum 50 batted balls on sliders.
All this, however, leads to a match of wits.

As noted before, the D-backs have hit Gray's fastball well. That's consistent with the rest of baseball. Gray has given up a .321 batting average and .511 slugging percentage on the four-seam fastball. The slugging percentage yielded is 59th-best out of 81 starters (minimum 150 at-bats).
Given that, and the fact that 79 of Gray's 112 strikeouts have come on breaking balls, one would think to pocket the fastball.
But take another look at the graphic chart above at the number of swings and misses out of the strike zone. In order to entice hitters to swing, he has to make them honor the fastball. To that end, Gray has varied his strategy.
In the June 30 game at Chase, he threw his four-seam fastball 51.4 percent of the time and his slider 35 percent in the first three innings, then went to the fastball a little more -- 57 percent in innings 4-7, with 30 percent sliders.
The second meeting he began with more fastballs -- 60 percent four-seamers and 29 percent sliders in innings 1-3. But in innings 4-7, he was a different guy -- just 36 percent fastballs and 23 percent sliders, but 40 percent curveballs.

Gray and catcher Jonathan Lucroy expect to devise a plan to play to Gray's strengths and keep the D-backs off balance. The preparation will help with expected butterflies.
"There's definitely going to be some thoughts because of all the atmosphere," Gray said. "You can't ignore where you're at in the season and forget about it. Then again, it is taking it as another start and doing the best you can."
And if he feels a little lost, Gray can simply follow a literal path laid out for him.