PHILADELPHIA -- So much has changed in the past three weeks.

For the Phillies.

For the Mets.

For Taijuan Walker.

The Phillies beat the Mets on Friday night at Citizens Bank Park, 5-1. They have won 14 of 18 since June 3 to improve to 39-36, while the Mets have lost 14 of 18 since they completed a sweep of the Phillies at Citi Field on June 1. They are 34-41.

“That’s what we were asking ourselves the whole first 50-60 games: ‘What’s the problem? What is it? What is it?’” Trea Turner said about the three-week turnaround. “We’re playing better baseball. We’re getting leads, holding them, playing good defense, winning close games, just doing a little bit of everything.”

Walker struggled against the Mets on June 1, falling to 4-3 with a 5.65 ERA. He pitched only four innings that afternoon because the Phillies could see he did not have his best stuff. Even Walker said he could not get going that day. His four-seam fastball averaged 92 mph, down 1.1 mph from his season average and 1.7 mph from his 2022 average. He threw only one pitch 93 mph or harder against the Mets. He had never thrown fewer than four in any start in his career.

Walker insisted that he was healthy, but it was fair to wonder. He had experienced an elbow issue earlier this season. He seemed gimpy at times.

But Walker is 4-0 with a 0.69 ERA (two earned runs in 26 innings) in four starts since then, including Friday, when he allowed one run in six innings against the Mets. It is the first time he has won four consecutive starts since 2015. He has a 2.63 ERA (16 earned runs in 54 2/3 innings) in his past 10 starts.

Walker’s four-seam fastball averaged 93.9 mph on Friday. It has averaged 94.4 mph in his last four.

“It’s the uptick in velocity, my body is feeling good,” Walker said about his turnaround. “I feel like when my velocity is up, I think everything just plays a little bit better. The splitter is better. The cutter has been really good lately. I’ve been throwing it a lot more. I think just mixing all my pitches and throwing strikes.”

Walker got five swings and misses on his splitter, which is his money pitch. He got two swings and misses on the cutter.

"[Walker] pitched really well tonight,” said Mets center fielder Brandon Nimmo, who homered in the third. “He made adjustments from the last start that he had against us. His velo was up a little bit, which is obviously good for him. That always helps your stuff to play better, and his splitter."

The Phillies took advantage of two Mets gaffes in the outfield to score their five runs. Kyle Schwarber reached base to open the first when Nimmo dropped a catchable ball in center field. The error led to two runs.

The Phillies scored three more in the sixth to take a 5-1 lead after Brandon Marsh hit a pop fly to shallow left field that should have been caught easily, but instead fell between Francisco Lindor and Tommy Pham to plate the first run of the inning.

Three weeks ago, the Phillies were answering questions about their miscues. Three weeks later, it’s the Mets. FanGraphs had the Mets’ postseason odds at 67.3 percent on June 1. The Phillies’ chances stood at 23.3 percent.

But the Phillies left the ballpark on Friday with a 43.8 percent chance to make the postseason. The Mets have a 16.8 percent chance.

“It’s completely different,” Phillies manager Rob Thomson said. “We weren’t playing well at the time. But it’s not that I didn’t have confidence in them, because I always do. Because I know how good we can be. But right now we’re in a stretch where we’re playing really well. We just need to keep it going.”