"J.K. has looked better every day," Harbaugh said. "His quickness is kind of back."
Dobbins was activated off the physically unable to perform list Aug. 8, which was nearly a year since he tore his left ACL in last year's preseason finale. It looked like he lacked his usual burst in his first practices back, but he has been more explosive recently.
The Ravens won't say whether Dobbins will be ready for the Sept. 11 opener at the New York Jets. Without Dobbins playing in the preseason, Baltimore struggled to run the ball with Mike Davis and Justice Hill.
Drake practiced with the Ravens for the first time Wednesday after signing with the team.
Harbaugh said the addition of Drake improves the Ravens' backfield and is not a reflection of Dobbins' status.
"We've been known to run the ball a little bit," Harbaugh said. "So you get a running back out there who fits what we do -- a talented guy who wants to be here -- we feel like it was a good move for us."