CHICAGO — Taijuan Walker has resumed playing catch with his waning splitter, and the Phillies are encouraged by the early results.

Walker, placed on the injured list June 23 with a blister inflammation of his right index finger, long-tossed and played catch in what manager Rob Thomson described as a “heavy day” before Wednesday night’s game against the Chicago Cubs at Wrigley Field.

But unlike Bryce Harper (left hamstring strain) and Kyle Schwarber (left groin strain), who likely will return next week, and even JT Realmuto (right knee surgery), who isn’t far behind, Walker’s return isn’t imminent.

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“We’ve got to build him up,” Thomson said. “He’s been down for a little bit now, so it’s going to take a little bit to build him up.”

The blister — Thomson called it a “hot spot” — on Walker’s index finger was making it difficult to throw his signature splitter. After using the pitch one-third of the time last season and holding opponents to a .205 average and .295 slugging, he has thrown it only 17.6% of the time this season, with opponents teeing off to a .426 average and .704 slugging.

Walker went several days without throwing a splitter at all to allow his finger to heal. Although he still hasn’t thrown it from a mound, according to Thomson, he recently tested it off flat ground.

“He’s just playing catch with it,” Thomson said, “but I guess the action on it is pretty good.”

When Walker was sidelined last month, Thomson said he wouldn’t return to the rotation until he figured out how to throw the splitter more effectively.

But circumstances have changed. Veteran righty Spencer Turnbull, who stepped into the rotation for Walker, strained a muscle behind his shoulder in a start last week in Detroit and will miss 6-8 weeks.

The No. 5 spot in the rotation is occupied now by 25-year-old rookie Michael Mercado. He gave up one run in five innings and won his first major-league start Tuesday night at Wrigley Field and will make two more starts before the All-Star break, including Sunday in Atlanta.

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But the Phillies still seem to view Walker’s absence as an opportunity for a reset in the second half. They put him on a program in which he’s throwing weighted balls in an attempt to stall a gradual decline in his fastball velocity. Since 2021, his average velocity has slipped from 94.5 mph to 93.7 mph, 92.8 mph, and 91.3 this season.

It’s too soon, according to Thomson, to know if the weighted-ball training is working because the Phillies haven’t gotten radar readings.

“Hopefully his split comes back and we add a little bit of velocity,” Thomson said. “He’s coming along fine.”

Harper, Sánchez rewarded

When Thomson informed the team Tuesday that Bryce Harper won National League player of the month for a second month in a row, players applauded in the clubhouse.

But when they heard that Cristopher Sánchez was named NL pitcher of the month, they went wild.

“The place just erupted,” Thomson said. “They know how far he’s come, the work that he’s put in, and they appreciate it. It hits my heart pretty good because he’s certainly earned it. He pitched well.”

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Sánchez went 3-0 with a 1.64 ERA and 0.82 walks/hits per inning pitched in five June starts. He struck out 23 batters, walked four, and held opponents to a .207 average.

Harper, meanwhile, batted .374/.452/.714, with seven home runs, 16 RBIs, 10 doubles, 13 walks, and 20 runs scored in 23 games.

It marked the first time a Phillies player and pitcher won the respective monthly awards since Mike Schmidt and Steve Carlton in May 1980 — when the Phillies wound up winning the World Series.

Hamstrung

Thomson said the Phillies have looked into the frequency of hamstring injuries this season. Trea Turner, Brandon Marsh, and most recently, Harper landed on the injured list with hamstring strains.

The initial conclusion: There’s no common denominator.

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“It seems to me, right now, it’s just kind of coincidence,” Thomson said. “Two of them were pretty mild. The Turner one was the big one. Guys are gonna get hurt. It’s just part of the game.”

Turner missed six weeks after straining his left hamstring on May 3. Marsh missed only two weeks last month, and Harper likely will return next week after straining his hamstring last Thursday night.

Additional bases

The Phillies sent Turnbull to their spring-training facility in Clearwater, Fla., to begin his rehab. … Sánchez (6-3, 2.41 ERA) is scheduled to start the Fourth of July series finale against Cubs righty Jameson Taillon (4-4, 3.03).