The key for Taijuan Walker is ‘staying ahead.’ Here’s how the Phillies are trying to get him there.

KANSAS CITY, Mo. — Salvador Perez has a chase rate of 43.2%. It is one of the highest marks in baseball. He sees a below-average percentage of pitches in the zone because pitchers know what happens when they throw it in the zone.

Taijuan Walker saw it himself on Friday night. In the third inning, he threw a sinker just outside that Perez fouled off. Then, he threw a sweeper in middle bottom part of the zone that Perez sent 434 feet into the left-field stands.

Given Perez’s proclivity for chasing, it wasn’t the best situation to throw a strike. Walker’s problems are dizzying and extensive. His velocity has ticked up, but is not as high as it was in previous seasons. His chase rate and strikeout rate have plummeted to 23.9% and 18.5%, respectively, as his walk rate has risen to career-high 9.8%. Hitters are crushing the balls he throws in the zone.

» READ MORE: The Phillies wanted to ‘try to shore up some areas’ on offense, so they made a change to their batting practice routine

But the Phillies believe that above all, his biggest problem is his inability to get ahead and stay ahead in the count. Of course, every pitcher wants to pitch in favorable counts, but for Walker, it is especially important. His splits reflect that.

He’s pitched in 68 at-bats where the batter is ahead. Hitters have hit .353/.542/.750 with a 1.292 OPS in those counts. When Walker is pitching ahead — over 88 at-bats this season — hitters have hit .216/.217/.330 with a .547 OPS.

It’s a wild fluctuation, one the Phillies are very aware of. Walker has pitched in only 21 at-bats with a 0-2 count this season, 35 with a 1-2 count, and 38 with a 2-2 count. For reference, Zack Wheeler has pitched in 65 0-2 at-bats so far, 95 1-2 at-bats, and 90 2-2 at-bats.

It’s not an easy problem to solve, but the Phillies are trying to solve it. Pitching coach Caleb Cotham said that Walker has been working in between starts on game-simulated bullpens. He’s not the only starter who does this, but he does it more than most.

The idea is to prepare him for situations he’ll encounter in games.

“It’s working through hitters and thinking about what he just did — basically practicing thinking in the moment,” Cotham said. “Simulating a true at-bat with a true reaction vs. no hitter in there, no outcome of the pitch. Because if you throw a split and you’re not in that mode, you might get frustrated at a bounced split, but if you’re 0-1 and you say, ‘This guy I’m facing is a chaser, he chases splits a lot,’ and you throw that, now I can contextualize the bullpen a little bit more.”

» READ MORE: The Phillies expected more from Bryson Stott and Brandon Marsh. Here’s how they’re dealing with ‘a game of failure.’

Manager Rob Thomson was asked on Saturday if Walker would make his next scheduled start. He declined to get into specifics, but said they are “working on a couple of things.”

“We’re trying to figure it out,” Thomson said.

Consider getting in better counts a big piece of the puzzle.

“I think there’s a lot of ways to stay ahead, right?” Cotham said. “One is throw first-pitch strikes. Which last night wasn’t as good as he’s capable of, but it wasn’t like he’s throwing ball one all the time, either.

“I think it’s more inside the count — when to be greedy, and when to not. And that ties into a bit of the chase [rate]. We’re trying to find ways to create strikes by asking questions of the hitter that make him chase things. What you don’t want to be is very obvious, in a sense. So then, if their eyes can look in one place, then they know what’s a strike/ball.

“So maybe it’s creating a little more indecision in the strike zone. Being kind of random, different spots, staying out of the center column a little bit more. I think if you stay in one column or one level of the zone, it’s easier for hitters to train their eyes on certain things. The overall strike rate ends up shaking out pretty good. I mean, 60% last night, 66% last time. It’s more inside the count. Winning those 1-1 counts, turning those into 1-2s and now 2-1s. If he turns the 1-1 to [Hunter] Renfroe into a 1-2, it’s a little bit of a different at-bat than a 2-1 sinker — now you do need to throw a strike. The hitter knows you need to throw a strike.”

That indecision can come from pitch mix, or switching up locations. It can come from making an adjustment in a game, or even in an at-bat. That is what the Phillies want to Walker to improve on.

“I think it’s more about staying ahead,” Cotham said. “Getting ahead is one of our core principles. The best time to throw a strike is 0-0. There’s very, very few times where it makes sense to at least think [about throwing] a ball, and even then, you’re placing a big bet that they’re going to swing at a ball.

“But I would say it’s more how we navigate through the count, through the at-bat, and stay ahead. And keep putting pressure, and asking the hitter to make tough decisions. His stuff is trending up. The velocity is up, the splitter is better. So it’s more dialing in, not being obvious. Really just commanding the count. Getting 0-2, 1-2, three pitches or less, and getting weak contact along the way.”

Triple A starter Kolby Allard will start on Sunday, so the Phillies starters can get an extra day of rest, Thomson announced on Saturday. … Spencer Turnbull (right lat strain) has resumed his throwing program and began playing catch this week.