Just about a month ago, Mel Kiper posted his first mock draft, in which he had the 49ers grabbing OT Trent Williams and S Earl Thomas.  While folks may disagree on the players, it certainly fills two areas of need.  Offensive tackle has been discussed ad nauseum, while the secondary could use some help alongside Dashon Goldson.

Earlier today, Mel laid out his "pre-combine" mock draft.  What's changed since then?  Well, the Senior Bowl.  And I suppose Mel's mind has changed since then, sometimes in rather considerable ways.  Whereas 1.0 had the 49ers grabbing Earl Thomas, this time around Thomas has dropped out of the first round entirely.  Anybody have thoughts on why that is?  Because Mel certainly doesn't say why.  I find this particularly interesting because in his top 5 at each position, Mel ranks Thomas #2 and Taylor Mays #3 among safeties, and yet he has Mays going #24 to the Eagles.  Is it based on different skill sets they bring to the table?  I'm not really sure.

Anyways, on to the 49ers two picks, with Mel's insight:

#13: C.J. Spiller, RB, Clemson
Kiper: In Spiller, the 49ers can add a player who complements Frank Gore in a way I don't think Glen Coffee can. Spiller is a home run threat and should spell Gore and diversify the offense. He also provides an upgrade in the return game.

#16: Trent Williams, OT, Oklahoma
Kiper: Considering how good Williams is, even at a position that normally doesn't draw high-to-mid first-round picks, getting him here would be of solid value. Williams could step in immediately at right tackle, and the 49ers would upgrade up front.