I don't recall too many times the OL had "great trouble" blocking 3 rushers, particularly when they kept an extra blocker in, so I'd have to see some evidence to back up your belief. That's not to say there weren't problems in pass protection - that was obvious to everyone. As for evidence, in one of his post season columns, McGinn wrote that opponents blitzed on about 20% of pass plays, which was down from 23.7% the previous year - but that's only about a 4% difference from 2011. He also wrote that the average release time of Rodgers' 9 INTs was 3.11 seconds. (Remember the 2.5 second "clock" McCarthy installed in TC?) I haven't seen the average time per sack but I'll bet it's longer. That of course points to Rodgers and/or the receivers being somewhat culpable as well.
The OL was charged with 35 of the 55 sacks surrendered and Rodgers was responsible for 14. Some here don't like to read it but the biggest problem on the OL was Marshall Newhouse. He surrendered nearly twice as many pressures (42.5) as any other OL. That's the most recorded by jsonline since they began keeping track of 'em in 1999. Some here want to blame Campen for that but how many OL coaches can make an NFL-quality starting LT on a passing team out of a player picked as a compensation pick after the 5th round of the draft? IMO if that guy becomes an adequate backup NFL OT, that's a feather in the coaching staff's caps. Newhouse shouldn't have to be the one starting. Thompson provided Sherrod as an alternative and due to the fault of no one, he got hurt. I hope we see an open competition at LT when TC begins. If Sherrod can't do it, I would like to see Bulaga and one of the youngsters like Datko given a shot. Of course I'd love it, but I don't think the Packers need a dominant OL. Fix the problem at LT and I think they'd be plenty good enough.
There is hope for the OL. If you haven't already, I suggest finding the McGinn review of the OL in the playoff game at San Fran as it's very instructive. The OL received a grade of 4.5 out of 5 - they showed up against a very good front 7. They didn't give up a "bad" run. EDS had a very strong game, delivering a "heavy punch" and "hits hard, works extremely hard and goes after people. He also was the only lineman who didn't yield a pressure." He played much better than Saturday last season IMO. Sitton gave up 0.5 pressures. Lang matched up against Justin Smith and "held up just fine". Barclay gave up two pressures and Newhouse's "maddening inconsistencies were evident…"
Having said all that if they have a LT prospect rated higher than a player on defense I'm all in favor of them drafting the LT. But because there are at least three players on the roster who can upgrade the LT spot (including Newhouse himself - if he was just determined to finish plays he'd be significantly better); because those who argue the D was much more responsible for the debacle in San Fran than the O have a point and stats to back them up; and because IMO there is a huge need for another playmaker on defense, I'm hoping a defender is the obvious pick at #26.