"There's satisfaction, because so much work has gone into this," Middlebrooks said.
Once a Top 100 prospect, Middlebrooks hit 32 home runs for the Red Sox in his first 169 Major League games in 2012-13. But those productive seasons were interrupted by a broken wrist in August 2012, which Middlebrooks at first overcame, but later succumbed to.
His bat speed diminished, he hit .191/.256/.265 for the World Series champion Red Sox in 2014, losing his grip on the third-base job because of injuries and underperformance. After signing free agent Pablo Sandoval, Boston traded Middlebrooks to the Padres, for whom he hit .212/.241/.361 in 83 games in 2015.
He inked a Minor League contract with Milwaukee last winter and went to work remaking his swing.
"My whole life, I hit the same," Middlebrooks said. "I had a lot of bat speed, so I could get away with a lot of flaws in my swing. [When] you break three bones in your wrist, you lose a little bit of that -- and it was my top hand.
"So I fought that for years, saying, 'I've hit this way my whole life. I should still be able to hit this way.' Finally, I broke it down and decided ... I have to make a change."
Sidelined for most of April by an oblique injury, Middlebrooks struggled through May at Colorado Springs, while working on his swing with manager Rick Sweet and hitting coach Bob Skube. He found his stride in June, hitting .371 with seven home runs and 31 RBIs in his final 32 games prior to Monday's promotion.
He will back up Aaron Hill at third base and Chris Carter at first. With Keon Broxton optioned to Triple-A to make room for Middlebrooks' arrival, the Brewers have only three true outfielders on the roster. Utility man Hernan Perez has occasionally been starting in right, however, and Jake Elmore can also play the corners.
The Brewers' odd 11 a.m. local start in Washington, D.C., on Monday was not unfamiliar to Middlebrooks, who played similar games on Patriots' Day with the Red Sox. Putting on a Major League uniform again was better than any jolt of caffeine.
"I'm wide awake today, trust me," Middlebrooks said.