Minnesota scored twice on balks and took advantage of a pair of errors by the Red Sox, who have allowed 21 runs in their last two games. Baker (2-2) allowed seven hits, struck out eight and walked one for the Twins, who have won three straight for just the second time this season.
J.D. Drew homered in the second and Adrian Gonzalez went deep in the fourth, but that was all the offense for Boston, which has lost three straight.
Red Sox manager Terry Francona was ejected in the second inning after Tim Wakefield (0-1) was called for a balk. Wakefield allowed eight runs, six earned, and nine hits in 4 1-3 innings.
Plouffe had two hits, including his solo drive in the first, and scored three times as the Twins had one of their best offensive nights of the season. Their 12 hits were one short of their season high and the nine runs were also one less than their most this year.
Minnesota got a little help from the Red Sox, who fell to 3-5 on an 11-game homestand.
The Twins scored three in the second after loading the bases with no outs. Wakefield nearly got out of it by getting Drew Butera to fly out and striking out Alexi Casilla, but Denard Span got a grounder past first baseman Gonzalez and two runs scored.
Ben Revere, who reached on a single, then came in from third when Wakefield was called for a balk while trying to pick off Span. Boston got Span in a rundown and tagged him, but the out was waved off when home plate umpire Angel Hernandez called a balk.
Francona was ejected for storming out to argue the call, which he proceeded to do for several minutes after Hernandez tossed him. Crew chief Joe West had to keep Francona away from Hernandez and was bumped a few times while Francona fumed.
Gonzalez's long drive in the fourth struck one of the giant signs above the seats on the Green Monster and cut Minnesota's lead to 4-2. But Boston unraveled again defensively in the fifth.
Danny Valencia doubled to left with the bases loaded, driving in two more runs for the Twins. Wakefield was replaced by Alfredo Aceves, who inherited runners on second and third with just one out. Aceves struck out Revere and got Butera to hit a grounder to shortstop Jed Lowrie, who misplayed the ball. The error allowed Michael Cuddyer and Valencia to score, putting the Twins up 8-2.
The Twins got another run in the sixth on two more mistakes by the Red Sox. Plouffe, who reached on a fielder's choice, stole second and went to third when Lowrie missed the throw from home. Plouffe then scored when Aceves was called for a balk before he could get off the next pitch.
Notes
After missing badly on a knuckleball and falling behind 1-2, Plouffe belted the next pitch for a homer to left. It was the third of his career. … Baker struck out leadoff batter Jacoby Ellsbury on his first three pitches. … Twins manager Ron Gardenhire said LHP Francisco Liriano's scheduled start Monday will depend on how he feels Saturday. Liriano was sick Friday and stayed at the team's hotel. … Francona said before the game he might go to the Heat-Celtics playoff game after the Twins and Red Sox play Saturday afternoon — but don't look for him courtside. "My seats are in hiding position," he said. "They're up where you can get in and out and you're not bringing notice to yourself."