McCullers (forearm) threw 20 pitches off the mound Friday with his fastball velocity bumping up to 87 mph, Julia Morales of AT&T SportsNet Southwest reports.
In Tuesday's bullpen session he hit 86 mph with his fastball, so he is making gradual improvements. It doesn't sound like he is particularly close to returning to the big-league rotation, given where his velocity is and the fact he hasn't faced hitters yet.