Chris Bruce and Andrew Mooney of HSAC do a bang up job using WPA and EPA to analyze Tim Tebow's clutchitude.
So, broadly, Tebow has indeed exhibited “clutch” performance –– performing pretty ordinarily overall, but at a higher level when it matters most. Given our previous analysis of other quarterbacks who did this in their first year (including Tom Brady, Aaron Rodgers and Drew Brees), it’s unlikely that this is a sustainable course in the long run. However, it should be encouraging for Tebow fans that his performance has been improving in absolute terms.
I had the exact same Excel graph (QB WPA vs EPA) sitting on my desktop all week last week, looking for Tebow to be a giant outlier, exceeding his "expected WPA" enormously. He does, but it's not out of whack with what some other QBs have done in such short spans of time. (I even had a clever title for the accompanying post: The Power of Prayer.) Bruce and Andrew go a step further, and add their analysis of how 'clutch' first year QBs don't typically sustain that level of over-performance.
I suspect there is a bit of a selection bias/survivor effect at work. First-year QBs who 'over-perform' in clutch terms are more likely to survive into the pool of 2nd year QBs. And of those guys, the lucky/clutch ones are more likely to survive into their 3rd year, and so on.