BOSTON (CBSNewYork/AP) — This winter Brian Cashman and the Yankees front office went to work rebuilding their starting rotation. The result was signing a 36-year-old to a three-year contract, signing a 38-year-old with heart and knee problems, and trading for a 30-year-old who had never been healthy enough to make 30 starts.

Here’s a good question for New York’s general manager — what did he think was going to happen this season?

J.D. Martinez and Andrew Benintendi homered as the Boston Red Sox demolished New York’s beleaguered starting rotation for a third straight day, winning 9-5 on Saturday.

The Red Sox have outscored the Yankees 38-13 to win the first three of a four-game set. Boston ace Chris Sale goes in the series finale Sunday night, trying to sweep Domingo Germán and the AL East leaders.

This was the sixth straight game Boston has scored eight or more runs against the Yankees, the first time in the clubs’ 117-year rivalry.

MORE: Yankees Trade Deadline: 7 Reasons New York Has To Deal For An Ace Pitcher

The Yankees have lost three straight for the first time since June 11-14.

CC Sabathia (5-6) fared only slightly better than the previous six games by a New York starter (with him included Monday), giving up five runs and nine hits in 4 1/3 innings. In his last outing, the 39-year-old was tagged for seven runs in four innings.

Over the past seven games, New York’s starters have given up 52 runs — 48 earned — on 52 hits in 26 innings. Overall, the staff has been pounded for 73 runs, with 64 coming in the previous six, the most in a six-game stretch in the franchise’s illustrious history.

Sabathia’s – who appears to be fading fast in his final big league season – saw his season ERA balloon to 4.78. Every member of the Yankees starting staff now has an ERA well over 4. It’s putting even more pressure on Cashman to pay up and finally acquire an ace pitcher at the July 31 trade deadline — something he’s failed to do for two straight years.

Trailing 2-1 in the fourth, Martinez pushed Boston in front by hitting the first pitch he saw into the last row of Green Monster seats for a two-run homer. Michael Chavis added an RBI single that made it 4-2.

The Red Sox broke it open with three runs in the sixth against Chad Green. Sam Travis, who had three singles, hit an RBI single before Brock Holt and Mookie Betts each had a sacrifice fly.

The one bright spot was super utility man Gio Urshela, who went 4-for-4 with a solo homer and RBI single for New York.

UGLY NUMBERS:

Entering the day, the Yankees’ starters had major-league worsts in ERA (7.96), slugging % (.647), opponent’s OPS (1.010) and had allowed an MLB-high 26 homers since the All-Star break.

“There no question we’re going through a tough stretch right now on the mound and have had a rough week and that’s part of it,” manager Aaron Boone said before the game. “You hear me talk all the time: ‘162 and you’re going to get punched in the mouth once in a while.'”

TRAINER’S ROOM:

Boone said RHP Dellin Betances (right shoulder impingement) should be throwing off a mound this week and RHP Luis Severino (right rotator cuff inflammation) is set to start a throwing program.

INF DJ LeMahieu, who entered Saturday as the AL’s batting leader, was sidelined with a sore groin. Boone said he had an MRI before the game and “while I don’t think it’s something major, we wanted to get the testing done and see where we’re at with it.”

UP NEXT:

Yankees: Germán (12-2, 4.03 ERA) was tagged for a career-high eight runs in 3 2/3 innings in his last start.

(© Copyright 2019 CBS Broadcasting Inc. All Rights Reserved. The Associated Press contributed to this report.)