Brewers manager Ron Roenicke confirmed prior to Wednesday's game that Rodriguez was on his way to meet the team in Pittsburgh from Triple-A Nashville, a day before the team had to release him if he wasn't in the Major Leagues.
Because Rodriguez didn't make it to Pittsburgh in time for the game, the Brewers didn't make a corresponding roster move until after Wednesday's 3-1 loss to the Pirates. With the bullpen taxed of late, Milwaukee will go with an extra man in the bullpen for the time being, optioning Blake Lalli to Nashville.
Lalli, 30, had just three hits in 24 at-bats with the Brewers, appearing in five games at first base and one game at catcher.
To make room on the 40-man roster for Rodriguez, the Brewers moved infielder Taylor Green to the 60-day disabled list, as Green is out for the season after undergoing hip surgery.
Rodriguez, 31, was signed to a minor league deal on April 17 and appeared in four minor league games between advanced Class-A Brevard County and Triple-A Nashville.
Brewers general manager Doug Melvin was on hand to watch Rodriguez pitch Monday and Tuesday for Nashville. Rodriguez didn't allow a run, walked three and struck out seven in his four minor league innings.
According to the Nashville Sounds, Rodriguez hit 91 mph on the radar gun with his fastball during Tuesday's outing.
Acquired on July 12, 2011, from the New York Mets, Rodriguez was key in the team's run to the division title and the National League Championship Series. Rodriguez had a 1.86 ERA in 31 regular-season games with the Brewers and yielded just one run in five playoff innings.
In his first full season with the Brewers, Rodriguez went 2-7 with a 4.38 ERA in 78 games in 2012, but he lowered his ERA substantially by allowing just two earned runs in his final 15 innings.
Rodriguez went unsigned after the season but did pitch in the World Baseball Classic for Venezuela. His country's stay in the tournament was short-lived, but Rodriguez appeared in two of the three games, working 2 1/3 innings with a 3.86 ERA.
With 294 career saves, Rodriguez ranks 25th in baseball history and holds the single-season saves record for recording 62 in 2008 with the Angels.
Rodriguez has appeared in 682 games over the course of 11 seasons with the Angels, Mets and Brewers, posting a 2.70 career ERA in 720 2/3 innings. Rodriguez led the American League in saves three times and is a four-time All-Star.