The Yankees shook things up Friday afternoon when they traded for Rockies third baseman Ryan McMahon, a much-needed acquisition to strengthen an obvious weak spot.

McMahon was not in pinstripes yet for Friday night’s series opener against the Phillies, who exposed another area of great need for the Yankees just six days ahead of the trade deadline: the bullpen.

Will Warren was steady in a 5 2/3-inning start and the Yankees’ bats did their part with four solo homers, but Tim Hill, Luke Weaver, Ian Hamilton and Scott Effross each imploded in the Yankees’ 12-5 loss to the Phillies in front of 47,018 at a sold-out Yankee Stadium.

The Yankees (56-47) have lost 22 of their last 36 games and fell 5 1/2 games behind the AL East-leading Blue Jays, who defeated the Tigers, 6-2, in Detroit.

The Yankees’ defensive issues, which have garnered even more attention after they had four errors in Wednesday’s 8-4 loss in Toronto, appeared again on Friday with two more errors. Their 14 errors in July are tied for the most in MLB, according to researcher Katie Sharp.

Warren allowed two runs and five hits, striking out seven and walking three. He exited in a 2-2 game and did not factor into the decision.

Hill and Weaver each allowed two runs in two-thirds of an inning, Hamilton gave up two in the eighth and Effross allowed four in the ninth.

The Yankees held a 3-2 lead when Weaver relieved Hill — who got the final out of the sixth — with men on second and third and one out in the seventh.

Weaver got Nick Castellanos to hit a grounder to Paul Goldschmidt, who airmailed the throw home as Trea Turner scored to tie it at 3. Castellanos, reaching on what was ruled a single and an E-3, moved to second on the overthrow as Kyle Schwarber advanced to third.

J.T. Realmuto then launched a three-run homer to left off Weaver, handing the Phillies (59-44) a 6-3 lead.

The Yankees cut their deficit to 6-5 in the seventh. Anthony Volpe, on his bobblehead night, hit a 340-foot solo shot. Ben Rice had a pinch-hit, one-out single and later scored on Aaron Judge’s sac fly.

Hamilton recorded the first two outs in the eighth before allowing a two-run homer to Schwarber — his second of the night and 36th of the season — to make it 8-5.

Edmundo Sosa’s RBI single, Bryson Stott’s two-run double and Turner’s RBI triple off Effross blew things open in the ninth.

Cody Bellinger put the Yankees on the board first with a two-out solo shot, lifting Taijuan Walker’s 74.7-mph curveball into the second deck in rightfield for his 19th homer of the season.

With two outs in the second inning, Austin Wells made it 2-0 with a 372-foot solo homer of his own to the second level in right.

Warren allowed his only damage in the fifth, when Philadelphia tied it at 2 on Schwarber’s two-run blast — his 1,000th career hit.

Giancarlo Stanton hit the Yankees’ third two-out solo homer of the night in the sixth, hammering Walker’s 2-and-2 fastball into the Yankees’ bullpen to give them a 3-2 lead. Jazz Chisholm Jr. followed Stanton’s 435th career homer with an infield single, knocking Walker out of the game. Goldschmidt hit a bloop single off Tanner Banks, but Wells struck out to end the inning.