Totally agree with the OP! Just had a discussion with my brother about this. He said the same thing.
Shanahan coached liked McDermott. He has a minute and a half before the half to go down the field to score at least a field goal. Instead, he lets the time run. Tries one big play that would have gotten them the field goal, but it gets overturned on a penalty and they take the knee to go in tied at the half. They take a 10 point lead with 6 minutes to go in the game, get 6 yards on the first play. Then, Shanahan abandons the run and goes to the pass, where more can go wrong and where the difference makers on the KC defense do just that…Chris Jones knocking down passes, deflections at the line of scrimmage...etc. KC gets the ball back, they have 3rd and 15…could have ended the game here. SF rushes four, Mahomes heaves up a desperation pass, and seven men in coverage let Hill get wide open to catch it.
Shanahan did not learn from his failure with the Atlanta Super Bowl. Let’s hope McDermott was watching and did learn that while the game is undecided and you have a chance to put up more points, you play aggressively (aka Reid going for it on 4th down a number of times.) Once you have a two score lead, and your running game is working…that’s when you go conservative, to run clock, move the chains and keep the other offense off the field, and give your defense a breather.