No pitcher in baseball relies more on a split-fingered fastball than Hector Neris. It was the pitch that transformed him in 2013 from a middling minor-leaguer to a future major-league closer.

Neris threw the splitter last season for 65% of his pitches, had the seventh-most saves in the National League, and entered this season entrenched as the Phillies’ closer thanks to the splitter.

But after just 24 games this season, Neris has already seemed to lose hold of his ninth-inning duties. And it has a lot to do with his splitter.

“He’s just not getting the swings and misses that we’re used to seeing,” manager Joe Girardi said. “Some of it is location and we just have to continue to work on getting it down. The big thing with his split is that it has to look like a strike out of the hand and then it can disappear out of the zone. But if it’s a ball out of the hand, then it doesn’t do any good. And when it’s up, it’s not any good. There’s a fine line that he has to walk with that.”

With a two-run lead on Saturday, Girardi planned to use Neris for the eighth and new addition Brandon Workman for the ninth. It wasn’t a changing of the guard, Girardi said, but the Phillies were just playing the matchups. A night later, the Phillies again used Workman as their closer.

Neris had thrown just 12 pitches the night before, but he was not called to warm up Sunday when Workman ran into trouble in the ninth. It was instead David Hale, another new addition. Maybe the Phillies were again just playing the matchups. But more likely, Neris has pitched his way out of the ninth inning.

“Hector is going to get important outs,” Girardi said after Workman escaped the ninth inning. “I just didn’t use him tonight. But Hector is going to get important outs for us, too.”

Neris has thrown the splitter this season for 55% of his pitches, but it has not been effective. Opponents are hitting .400 against the splitter and slugging .500 against it. They hit .170 against it last season with a .283 slugging percentage. The average velocity (84.90) is nearly three MPH slower than it was last season.

The pitch has not been the same. He threw it six times on Saturday night and the Braves did not swing at any of them. Neris allowed three runs and recorded just one out as he flamed out in his first time in a new role. He has allowed runs in four of his last five outings and has thrown just 58% of his pitches for strikes.

The Phillies added three relievers - Workman, Hale, and Heath Hembree - on Friday and Girardi seems ready to throw all three into high-leverage spots.

Hembree made his Phillies debut in the sixth inning, stranded the runners he inherited on second and third base, and retired four of the five batters he faced. He’ll stay in the late-inning pecking order. That could mean less high-leverage work for Neris, especially after Tommy Hunter tackled the eighth inning on Sunday night. The Phillies seem to have four right-handers ahead of Neris, who was their closer less than a week ago.

“We matched it up to the way that we thought was most favorable to us,” Girardi said. “It worked. That’s the bottom line. It worked.”

Neris’ struggles have not been all on him. The infield made two errors behind him last Thursday against the Blue Jays and a defensive shift cost him a double play on Saturday night. But, the results of the ninth inning usually fall on the man on the mound. And those results have made Neris hard to trust when he can no longer rely on the pitch that made him reliable.

“We haven’t changed our thought process about Hector,” Girardi said. “We’ll continue to look at match-ups like the ones that are favorable to him and try to use him in those spots but we really haven’t said, ‘We’re not going to use Hector in high-leverage situations.’ ”

Extra bases

Jake Arrieta will start Tuesday night’s series opener in Washington. Aaron Nola will start Wednesday and Spencer Howard will start Thursday. ...The rotation for the Washington series likely means that Vince Velasquez is being moved to the bullpen as the Phillies will not need a sixth starter until a doubleheader on September 8.