At various times in the conversation Jim Tomsula used "unbelievable" "terrific" and "exciting" to describe new 49ers nose tackle Glenn Dorsey.

"Just doing a wonderful job" said Tomsula the 49ers' defensive-line coach. "Works at it and picks it up quick. I couldn't say enough good things about Glenn Dorsey and where he's at right now."

So why is Dorsey who signed a two-year free-agent contract with the 49ers in March playing with San Francisco's second string despite all that praise?

For one Dorsey mostly played defensive end when he was with Kansas City which used the fifth overall pick to select the former LSU star in 2008.

The 49ers envision him more – but not exclusively – as a nose tackle. That position requires much more technique and know-how and Dorsey 28 is still learning those skills.

"There's more stuff (opponents) can do to you" Dorsey said. "Inside it's a lot faster."

The second reason is that Ian Williams who entered the league undrafted in 2011 has settled in at the position and isn't giving it up easily. Williams has been practicing alongside fellow defensive linemen Justin Smith and Ray McDonald throughout training camp and started last week's game against the Broncos.