Your logic is correct. Along with that, I also believe the pass rush needs to be improved too especially from the interior. Coverage and pass rush obviously goes hand in hand. The Patriots did not get to Flacco enough to harass him and force him into making bad decisions, something he does when he's pressured consistently. Despite this, his receivers generated enough separation due to poor coverage and bad angles that it didn't matter much even if they did get to him often.
While the numerical value doesn't mean much, they did get 2 sacks (same as the 49ers amassed in the super bowl against the them), while the Ravens had zero sacks but forced a plethora of Patriots' mistakes through coverage in sub packages and LOS physicality. Just purely judging by those numbers one could make the claim that the Patriots generated more pressure than Baltimore but we know that isn't case and doesn't tell us the full story, as the game itself showed. It's all about forcing significant mistakes and so forth. This is a prime example of why glossy stats like sacks don't always mean your team is a great pass rushing team, as there are other factors involved. Sometimes its better to be great at coverage than it is to be good at generating pressure, because that too can fail. And when it does fail you're even more vulnerable (just ask Denver). At least if your team isn't getting any pressure you can hang your hat on the ability to cover enough to force mistakes and the like.
Moreover, the so called vaunted 49ers pass rush did not fare much better than the Patriots did statistically, especially against the Ravens' vertical passing game in the super bowl, not because they generated zero pass rush, but because their coverage in the secondary was abysmal, specifically Chris Culliver's on just about any Ravens pass catcher. They got burnt deep whether they got to Flacco or not. Their coverage in the back-end was the issue there.
The coverage in the middle of the Patriots defense was also abysmal and paid a huge factor in the Ravens decision to use shorter passing schemes to attack that area successfully in the second half. Gregory and Cole were liabilities of course, but Spikes for all his great instinctual play was the most flagrant culprit for their cover deficiency. He just does not possess the foot speed and lateral quickness to excel in any man-cover assignment and gets easily exposed in today's open spaced NFL. This can be improved, possibly with a talented prospect like KSU's Arthur Brown.