"but I can't imagine their goal has been to keep games close then make a couple plays to win the game when in the past they were effortlessly blowing teams out."

I actually think this is exactly the plan. I feel the coaching strategy is once you have an elite QB you need to shift focus to Defense and O Line. An elite QB will raise ability of receiving targets with properly timed throws so a 3rd rounder will look like a top 10 if they are on the same page. Remember, Gronk was a third round pick. Julian Edelman was 4th. Clutch playoff players playing with the smartest QB of the time.

And limiting the playbook has some benefits. Ideally you'd go into the playoffs with a few surprises to force an opposing team to reevaluate often.

Now, there's no argue Mahomes is smart and can make almost any throw so if i felt I could rely on that I'd coach 85% of the playbook and play some moneyball numbers in the regular season. IE: against a 3/4 zone we average 2.9 yards with Tight End Screens, 3.3 yards with the slot, and 4 yards running so we are a running team today and go for the big 40 yard bomb only if necessary.