Yates (knee) threw an abbreviated bullpen session Wednesday, Jeff Fletcher of the Orange County Register reports.
Yates said afterward that his knee felt healthy but that he still needs to sharpen his stuff before he's ready to pitch in a game. Sidelined by left knee inflammation, Yates is eligible for activation from the 15-day injured list April 6. It's unclear whether he'll be back on that date, but if he isn't it shouldn't be long after. Jordan Romano has seized the Angels' closer job for the time being, but Yates could work his way back into that mix.