I'm guessing you haven't watched much of Denver this year, but it's not the qb position that's holding them back. It's their poor run defense, terrible o-line, and complete lack of a running game since the CJ Anderson injury that might cost them the playoffs.
I kind of already answered this to Dirt, but Siemian has been better than you think and is not Denver's problem right now. In yards per game, he's 17th (right in the middle). Passer rating, he's 19th, between Philip Rivers and Jameis Winston. Yards per attempt, he's 15th. If you put much stock in ESPN's QBR (personally I don't, but I know some do), he's 16th. He's pretty much middle of the road in all qb stats, and he's actually playing better now than he was early in the season. In fact, in his last two starts, he's combined for to go 55-85 (65%), 4 touchdowns, no interceptions. And Denver lost both of those games.
Since CJ Anderson went down with injury, Denver has rushed 149 times for 439 yards. That's an average of 2.95 yards per carry, which is worst in the league. And that came against Tennessee (3rd ranked run defense), San Diego (7th ranked run defense), New Orleans (12th ranked run defense), Oakland (26th ranked run defense), and Kansas City (27th ranked run defense.
Therein lies the rub. I've been calling Romo injury prone back when most Cowboy fans still thought it was all just bad luck so you don't need to convince me of that. But if you will miss the playoffs without him the downside is no change in result (just wasted money). The upside is possibly winning a SB if you are Denver. And it's not like it's a 100% guarantee he gets injured and even if he does that he misses enough time to change the course of your season. If he plays enough to get you in the playoffs and then is healthy for the playoffs...who knows what could happen...
The Dallas OL is great, but this is so completely overblown at this point. The Cowboys aren't first in sacks allowed or QB hits and have a QB that makes them look even better because he doesn't hold the ball. Plus Dallas throws the ball less than other teams so if they threw it more their sacks/hits would go up. So a Cowboy QB gets hit what, a couple times less per game than Denver? They give up a sack every 5% of passing plays and Denver does every 7%. And with no facts I'd guess the coverage sacks are higher for Den because the Dallas line is better. So the guy running free at the QB type hits that put a lot of QBs out are maybe a handful more for Den than Dallas all year. So I kind disagree with the degree of impact everyone gives to the Cowboy OL. It's like the OL can achieve Peace in the Middle East at this point.
I'm confused by this, if Dallas has the better line, wouldn't their coverage sacks be higher? I can assure you, Denver isn't giving up a lot of coverage sacks this year.
Hey...I said I didn't have facts didn't I???
What I meant was the sacks when the QB held the ball for just 2 or 3 seconds with no one getting open and then the defender overpowered the OL and got a hold of him. These are not usually the sacks where the QB gets hit hard and hurt, but are still sacks. Kind of the pocket collapsing around him types. Assuming since Dallas individual OL are better that he gets an extra half second and throws it away before the sack???
Not sure about that my friend, if they did he might get injured again.
Right, I mean I know what a coverage sack is. My point is since Dallas has the better line, wouldn't a reasonable expectation be that more of their sacks allowed would be of the coverage sack variety? Since you wouldn't expect a better offensive line to get blown up as often. To me it makes sense, bad offensive line, more quick sacks allowed. Good offensive line, more coverage sacks allowed.
