NEW YORK -- Buck Showalter is the type of manager who pays attention to splits.

When it comes to how batters have fared against certain pitchers, in the daytime or at night, in various batting order positions or at certain ballparks, Showalter is all ears. He studies the data. Some bits, he finds meaningful. Others, he discards.

Why Kodai Senga has been a different pitcher at home versus on the road, however, Showalter cannot say. He’s aware of the splits, which grew more pronounced during Senga’s most dominant start of the season -- a seven-inning, one-hit performance at Citi Field on Tuesday night in a 2-0 win over the Phillies. In his new home ballpark, Senga has been an ace, with a 3-1 record and a 1.20 ERA. On the road, Senga has been ordinary, with a 2-2 mark and a 6.12 ERA.

“I’d love to have a concrete reason,” Showalter said. “I’m supposed to. But I can’t. We’ve looked at it early on, but I don’t know if it’s a big enough sampling for a guy just coming into the league for the first time. … It’s not like he hasn’t been able to get anybody out on the road. It’s just that he’s pitched really well at home.”

On Tuesday, Senga pitched really, really well at home. He struck out the first batter of the game, then two more to open the second inning. In the third, Senga allowed an opposite-field bloop single to Kody Clemens, which turned out to be the only hit against him. The Phillies mustered just one more all night, on a one-out single by Josh Harrison off David Robertson in the ninth.

“You have to respect the fact that he can throw 98 by you or that slider in on your hands,” said outfielder Brandon Nimmo. “That’s what makes that fork effective, because when it comes out, it looks just like the fastball. And then it’s just, ‘See you later.’ He did a really good job of using all of his pitches in any count tonight and had a really good offense off-balance.”

It was Nimmo who provided the game’s most significant assist, stretching his arm over the left-center-field fence to rob Nick Castellanos of a likely homer in the fourth inning. Lindor added the requisite offense, homering off Ranger Suárez in the bottom of the fourth to give the Mets a lead they never relinquished. But it was Senga who did the heavy lifting, completing seven innings on 100 pitches -- his deepest outing of the season, and easily his most efficient.

Over his last three home starts, Senga has produced a 0.47 ERA. Asked about the discrepancy between his home and road marks, Senga mentioned the difficulty of the Major League Baseball travel circuit, which is far more arduous than what he was used to in Japan. In an effort to combat that, Showalter sent Senga (and Wednesday starter Carlos Carrasco) home from Denver early so that they would have more time to recover from their days spent at altitude.

Whether that played a role in Senga’s success Tuesday is impossible to say, but this much is clear: he looked awfully comfortable on his home mound.

“At home, we have a lot of great fans here,” Senga said through interpreter Hiro Fujiwara. “I don’t want to disappoint them. I just want to win games for us.”

Technically speaking, the most important piece of Senga’s performance was his strike rate of 66 percent, his highest in a game so far. Getting ahead in counts with his fastball allowed Senga to use his signature ghost fork to aggrandized effect, resulting in a dozen whiffs on that pitch -- more than on all his other offerings combined.

“You can't stay through his fastball because you’re going to be underneath it. And you can't get on plane with his splitter because you’re going to be over the top of it,” Castellanos said. “It’s pretty similar to other pitchers that I've faced from Japan … They always have that slow, rhythmic delivery and a very explosive fastball that has good ride. And then they play that pitch that falls off the table.”

Lindor chalked Senga’s home/road splits up to the reality that he has made merely 10 Major League starts. He’s a rookie. As such, Senga is still figuring out some of the nuances of the American game, and his results may not have caught up to that yet. As Showalter put it, “It’s not like I’m going to make sure he pitches at home only.”

If the trend continues, however, the Mets will be looking forward to each Senga home start in an entirely different way.