As for the impact of Suh's presence, Caldwell said, "Obviously, he's a great player and he's also got great leadership ability. So to have him back here working amongst the group is going to be a great time for everybody."
Suh's decision to train on his own again for the first part of the off-season, rather than with his teammates, raised some questions about his true leadership ability, especially at a time when the Lions are implementing new systems following a coaching change.
"I've been a few places in my time," Caldwell said. "I can cite you so many different examples of guys that maybe weren't here during the time period that did a tremendous job just in terms of their leadership and those kinds of things.
"I don't expect him to be any different. I think he'll fit into that category as opposed to any other category you'd like to slide him into."
Asked to identify some of the other players he's seen over the years who had skipped the voluntary practices but were still quality leaders, Caldwell said, "I'm not going to name them all. I could go down the line. I can tell you a bunch of guys over the years but I'm not going to go through that."
Caldwell said he has stayed in contact with Suh, who could become an unrestricted free agent after the upcoming season if he doesn't sign a contract extension.
"We talk and we text," Caldwell said. "It will be great to have him back."
Caldwell described the three-day rookie mini-camp that ended Sunday as "outstanding."
"My 14th year in the National Football League, we've never had a group that was able to really devour so much information, and then not only that, they were able to go out and apply it," Caldwell said. "We got a lot of good work done. It was an impressive group."