This is good news:

"Rookie Kyle Van Noy appears to be starting to make an impact. The linebacker worked with the first-team defense during portions of Thursday’s practice and is starting to push to replace Ashlee Palmer at the SAM spot. After the draft, general manager Martin Mayhew indicated they believed Van Noy would be a starter pretty quickly. Tahir Whitehead also caught Caldwell’s attention, and while he isn’t a starter, the head coach said the third-year pro out of Temple continually shows up well on film. He won’t supplant Stephen Tulloch, but that, plus his special-teams ability, should put him in a good spot."

http://espn.go.com/blog/detroit-lions/post/_/id/9466/lions-camp-report-day-4