Diaz said his calf is still a little bit tight Thursday, which is why he's not sprinting full out on the bases, Patrick Saunders of The Denver Post reports.
Diaz was reinstated from the 10-day injured list June 30 after nursing a left calf strain. Since his return, the catcher is 6-for-18 with two doubles. However, it appears the calf injury is still lingering, as the 33-year-old says he will be careful about it.