Wondering three things about the Cowboys offense

Why was Jason Witten blocking on the final two plays from the Denver 2? If the Cowboys have somebody who will "win" a matchup, it's Witten, but on the final two plays he was asked to block against Denver's blitz. Why? He's supposed to be a red-zone threat. He's Tony Romo's favorite target. The Broncos played man to man on the final two plays. I'd like Witten against a linebacker for a 2-yard throw. But he's blocking. Just like he did at the goal line in Week 3 against Carolina. Where was Marion Barber? After the game Jerry Jones said Barber was healthy. Wade Phillips said he didn't know why Barber was limited to one carry in the second half. If he was healthy enough to get 10 carries in the first half and there was nothing new injury-wise after the game, according to the owner, then why was he held out? If you're going to go down, go down with your best. Barber is your best. Again, we have to assume he was healthy because there was no...