At approximately the same time Chicago White Sox’ pitcher Philip Humber completed a masterful perfect game against the Mariners in Seattle, the New York Yankees were on the opposite side of the country, beginning a perfectly exhilarating comeback against the Red Sox.

A day after New York spoiled Boston’s 100th birthday celebration of Fenway Park, the Yankees trailed, 9-0, after five innings, and it seemed as if the Red Sox would hold on for an important victory against their historic foe. But when Boston’s manager, Bobby Valentine, turned to his deeply struggling bullpen to finish the game, the Yankees powered 14 runs to stun the Red Sox, 15-9, on Saturday at Fenway. It was the kind of victory that has everyone wondering about the future of both Red Sox and their new manager. And although, the Yanks stole the first two games of three games –Sunday’s game was postponed due to rain– it offered more evidence that the balance of power in the American League East might have shifted and the real rivalry to watch is no longer the Yankees versus Red Sox, but the Yankees and the Tampa Bay Rays.

Invited to share the centennial of a 7-6 Red Sox win over the club from New York –then known as the Highlanders– the present day Yankees didn’t just attend the shindig. They trashed it. Most of the damage on Saturday was done by Nick Swisher and Mark Teixeira, who each drove in six runs as New York sent the already reeling Red Sox closer to the edge of desperation. Swisher hit a grand slam and a two-run double, and Teixeira homered from both sides of the plate and added a two-run double. The Yankees scored seven runs in both the seventh and eighth innings to complete the comeback and wipe away another poor start from Freddy Garcia. The Yankees tied a franchise record for the largest deficit overcome to win a game, equaling a mark that had been achieved four times.

The Red Sox’ pitching is atrocious, and has been for a while now, with an ERA over six since the start of September 2011. Former Yankee Alfredo Aceves, who surrendered the last of Boston’s 9-0 lead on Saturday, has an ERA of 24.00; Mark Melancon was sent to the minors earlier this week with an ERA close to 50; Justin Thomas’ ERA is 7.71; Vicente Padilla’s 9.82; Franklin Morales is one of the sturdier contributors, at 6.35. Boston had a 9-1 lead at the end of six innings, when Valentine made the decision to remove Felix Doubront after 99 pitches and Teixeria’s homer in the sixth. Valentine could have asked Doubront, who only gave up three hits to the Yanks, to at least start the seventh, but he felt that taking the young lefty out was “a no-brainer,” he said. But the Red Sox crumbled after Doubront retired and failed to protect a nine-run lead in front of a home crowd, leaving Valentine to question why he took out his starter. Padilla gave up Swisher’s grand slam. If a manager can’t count on his bullpen to hold an eight-run lead with nine outs to go, the problem goes way beyond that one decision. The Red Sox’ bullpen allowed 13 earned runs, the most it has given up since 1994.

The last time the Yanks overcame a 9-0 deficit to the Red Sox, they did it as a birthday gift to Derek Jeter, who turned 13 the day the team he would one day captain overcame Roger Clemens to win 12-11 in eleven innings at Yankee Stadium in 1987. The memory of that one is long forgotten, but what transpired on Saturday at Fenway Park may become a painful reminder, for years to come, to Boston fans of a season that’s spiraling out of control for the Red Sox. It certainly is one to remember, but one that should make us cherish the historic rivalry of years past.