Tebow is decidedly negative in both of those stats for the full season (-0.35 WPA and -13.3 EPA), but fortunately for the Broncos, the vast majority of the damage was confined to a meltdown in his single loss against the Lions. Here, I'm only going to focus on how the Broncos managed their three wins with Tebow at the helm.
There's a method to the Tebow madness. If we add his production from scrambles to his production from pass plays, he's in modest positive territory in his three wins:
Tebow Production by Play Type in His 3 Wins
The Broncos running game aside from Tebow has been effective thanks mostly to a single critical breakaway run by McGahee, and because the Broncos defense made the running strategy make sense. Here is how the running game minus Tebow breaks out by opponent.
DEN RB Running Production in the 3 Wins
It's been the defense that has really made the three wins possible. Keep in mind negative WPA and EPA numbers are good for defenses.
DEN Defensive Production in the 3 Wins
Against Miami, Tebow performed poorly until the last few minutes of regulation, when he rallied the Broncos to tie the game. His last-minute heroics may have been thrilling, but they were needed only because of the hole he had put his team in to that point. The game was ultimately won thanks to a Dolphins fumble and a 52-yard Matt Prater field goal.
The thriller against Oakland unfolded in much the same way. Carson Palmer threw three interceptions. Running back Willis McGahee tied the game with a 60-yard touchdown run at the end of the third quarter and totaled 0.30 WPA and 4.6 EPA. The Broncos took the lead for good on an Eddie Royal 80-yard punt return for a touchdown. Tebow played fairly well in his own right. He totaled 4.6 EPA and -0.03 WPA, threw no interceptions and gave up only two sacks.
Last Sunday’s victory over the Chiefs was mostly a defensive victory. Matt Cassel was held to 2.4 yards per attempt and was sacked four times. The Broncos’ defense held the Chiefs to 10 points, 7 really if we don’t count a pointless field goal in the final seconds. Tebow made a big impact in this game, as one of his two completions was a 56-yard touchdown pass.
In the three victories, Tebow totaled 0.03 WPA and 9.3 EPA (which includes all factors including delay of game and aborted plays), both of which are slightly above average. In other words, he helped more than hurt his team, but only barely. The Broncos’ running game, excluding Tebow, totaled 0.30 WPA and 0.3 EPA in those same games. (When the WPA and EPA are largely split like this, it indicates over-performance in game-changing clutch situations.) The Broncos’ defense was responsible for -0.53 WPA and -2.9 EPA in the three wins.