Eflin was placed on the 10-day injured list Tuesday with right patella tendonitis, Matt Breen of The Philadelphia Inquirer reports.
Eflin had surgery in 2016 to repair both patella tendons, so there figures to be a strong chance that the injury is related to those past issues. The Phillies aren't particularly concerned with the injury despite Eflin's history of knee troubles, but it's evidently enough of an issue for him to miss at least a turn or two in the rotation. The Phillies will go with a bullpen day in his place Wednesday against Atlanta. Eflin's move to the injured list can be backdated to Saturday, which leaves him eligible to be activated July 28.