PHILADELPHIA -- Taijuan Walker came away from his past few starts baffled as to why his fastball velocity was down considerably in the first inning, only to bounce back as the game went on.

This time, his velocity never came around. Nor did his command.

Walker never settled in after once again struggling out of the gate in the Phillies' 8-1 loss to the Twins on Saturday night at Citizens Bank Park. He issued a season-high six walks while also hitting a batter and serving up two home runs.

“Control is off, command is off, velocity is down,” manager Rob Thomson said. “So I think it's time to just give him a little breather.”

Walker, who did not have a 1-2-3 inning, issued three of his six walks -- which also matched his career high -- in the opening frame. He walked one batter each in the second and third, then gave up two homers in the fourth and permitted both a walk and a hit-by-pitch in the fifth.

“It might just be that time of year where I hit a little bit of a wall right now," Walker said.

With off-days coming on Monday and Thursday, as well as the six-man rotation the club has used since Michael Lorenzen’s arrival, Walker was already going to have seven days of rest before his next scheduled outing.

It sounds as if he could get a bit more.

"I think it's maybe just that time of year,” Thomson agreed. “He's been grinding pretty hard. We're going to look at maybe getting him some extra rest before his next start. I think that's probably the prudent thing to do."

Walker's four-seam fastball averaged just 91.2 mph against the Twins, his lowest in any of his 191 career outings. In fact, each of the three lowest average velocities in Walker's entire 11-year career have all come within the past month. His four-seamer averaged just 91.4 mph on July 15 and 91.5 mph on July 31.

In that July 31 outing, however, Walker's velocity came back as the night went on. He hit 94 mph multiple times, including a 94.1 mph fastball in the seventh inning.

On Saturday, he maxed out at 93.1 mph. None of his other 15 four-seamers exceeded 92.4 mph.

“I know we have a couple off-days coming up,” Walker said, “so hopefully I'll get a couple extra days of rest and the velocity picks back up.”

Without his typical velocity, Walker -- who insisted that he feels fine physically -- has been relying far less on his fastball. 

In April and May, he threw his four-seamer 23% of the time – his second-most-used pitch. Since June 1, Walker’s four-seamer usage is just 11.8%, making it his No. 4 offering.

"He's just not able to command the fastball as well as he has earlier in the year,” catcher J.T. Realmuto said. “And when you're not using your fastball as much, the other team is obviously going to pick up on that and the offspeed stuff is going to be less effective. That's the problem he's run into the last couple of starts."

And without his best fastball, Walker can’t risk making a mistake and leaving a meatball over the middle of the plate.

“A 90 mph fastball in the big leagues isn't going to get the job done,” Walker said.

The frustrating part for Walker is that he doesn’t feel any different than he did in June, when he went 5-1 with a 1.50 ERA, 34 strikeouts and 10 walks. 

He took the mound Saturday night hoping to see the scoreboard flash in the low-to-mid 90s, only to see an 88.9 mph pop up to Twins leadoff hitter Edouard Julien.

That's where the entire gameplan shifts.

"It's something that we talk about a little bit before the game,” Realmuto said. “But we're still waiting to see in the first inning where his velo is at before we really make a decision on how we're going to use it."

Whether it’s simply taking advantage of the two off-days or skipping Walker’s next turn to give him an extended layoff, he’s hoping some extra rest will solve the mystery surrounding his velocity dip.

“A month and a half ago, the velo was good, I was feeling really good, and right now, it's frustrating because I feel like I'm not at my best,” Walker said. “I'm getting by, but to not be at my best at this time when the offense is rolling and the defense is playing good, I really want to be out there helping the team.”