It is not obvious, neither does it make sense, sorry.
If your good OL can give your QB comfortable 3 seconds, and he can gain another 2 or 3 seconds scrambling, the odds of the passing offense succeeding goes up. So, if the baseline time given by the OL goes up with good OL players, an offense will take it 100% of the time. I can't see why you cannot see it.
Hmm...comebacks do not happen just because a team keeps doing onside kicks and keeps the ball, you know. Defenses give QB margins for error and keep their teams alive in games. Yes, you need the QB to finish the job but a sack or turnover generated by the DL can flip field position well if you have play makers that can get your QB the ball back.
Eli Manning 2007 and 2011, his comebacks do not happen if his D did not keep the score within striking distance for his 4th qtr. plays. Tom Brady, his 2014 comeback, down 10 in the 4th qtr. does not happen if his D does not force 3 and outs vs Russell Wilson.
Let us not diminish the value of playmakers on D just because the QB touches the ball every snap.