Tigers trainer Kevin Rand said Villarreal's issues warranting the MRI were about "grip strength."
"The MRI shows inflammation in and around the flexor (tendon) where it attaches," said Rand, "but no major structural damage.
"We'll treat it symptomatically until he's ready to go back out there. We just have to get it quiet."
Villarreal complained about weakness in his elbow on Sunday after a couple of ineffective appearances. Before that, he had been a key member of the bullpen. On the podcast, we joked that he might be the only member of the bullpen left who fans have faith in.
Villarreal has a 2.41 ERA in 35 games (37 1/3 innings). He has a 11.6 strikeouts per nine innings rate to go with 4.6 walks per nine innings.