TE Juwan Johnson undergoing surgery for foot injury and expected to miss camp time

Good amount of time.....half or most of training camp.
The 6 week break in between minicamp and training camp should allow Juwan to almost fully heal for the majority of training camp reps if this is a 6-7 week type of recovery.

Fortunately it’s happening during minicamp and not first day of training camp or preseason week 1