im with you that there if far to much stock put into the combine, but unfortunately for someone like davis this is really his best and only chance to get noticed by pro-scouts.
with that said i think that for lineman the 3 cone, times in the 10 yard and 20 yard splits in the 40, and the 20 yard shuttle should be a better evaluation of explosiveness of a D-lineman. the only problem with davis running the 40 on the nfl website is that he didn't look very fast off of the line.