I think what also worked well for Picardo was his ability to work well with other great actors in the cast. Mulgrew, Ryan, Philips, Russ, Dawson, Lien & McNiel all had great moments in Voyager when paired up with him be it a scene or the entire ep. He was also one of the few actors on the series like Mulgrew, Dawson & Ryan that could carry an ep. all by themselves. I think it shows great skill as an actor to be in a scene by yourself and you're supposed to be talking to the computer or CGI image and act or react like there is actually something there talking back to you.