NFL teams almost never go for it when they shouldn't, rarely go for it when it's a toss-up, and usually kick when the model has a moderate "go for it" lean.
They are still very conservative
Another view:
NFL teams almost always kick when they should, but often kick when they should be going for it unless the "go for it" recommendation is extremely strong
The worst decision of the year, by far, was Kliff Kingsbury sending out his kicker on 4th & 1, down 3, with 1:58 left in the game against the Dolphins.
One could argue that this decision cost his team a playoff spot.
Taking a closer look at ESPN's win probability model and this spike in Cleveland's WP was caused by a 9 yard Baltimore run on 1st & 10, which caused CLE WP to go from 55% to 75%
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In ESPN's win probability model, a 4 yard Trace McSorley run on 1st & 10 with more than 13 minutes left increased Cleveland's win probability from 18% to 34%