Rodriguez (back) threw off flat ground in the bullpen Saturday, Rhett Bollinger of MLB.com reports.
The Angels placed Rodriguez on the 15-day injured list Monday due to low-back inflammation, but his MRI came back negative. The fact that Rodriguez hasn't been shut down from throwing provides further reason for optimism, though the team will likely proceed cautiously from here given his injury history. Rodriguez has gone 2-2 with an 8.06 ERA, 1.83 WHIP and 24:15 K:BB in six starts and 25.2 innings for the big club so far this season.