It is not hyperbole to say that Nick Foles’s performance Sunday night was one of the greatest at the quarterback position in playoff history. Not just for a backup. Not just recent memory. Anyone, ever. Against the league’s top scoring defense in the regular season, Foles put on a clinic that was unmatched against the Vikings this year. His 92.9 overall grade was, in fact, the third-highest single-game grade we gave out at the quarterback position all year long.

Foles could have been facing a Big 12 defense, and few would have expected him to play the way he did on Sunday. That doesn’t mean, however, that his performance was unprecedented. For a quarterback who qualifies as a journeyman at this point, he’s had some of the highest-graded games we’ve ever awarded at the position. At the same time, he’s achieved some of the lowest as well. So how good is Nick Foles, and how well should we expect him to play in the Super Bowl? To answer that question, we’ll have to travel back a little over four years ago.

In Week 7 of the 2013 season, Foles made his third start of that season. He won his first two, racking up five touchdown passes with zero picks in the process. Chip Kelly’s offense looked as though it had found its signal-caller of the future. Then the division rival Cowboys came to town, with both teams sitting at 3-3 overall.

In the first half he dropped back to pass 25 times, completing only 11 of them for 64 yards. He overthrew six of his targeted passes and only earned two positive grades. Foles only made it a handful of plays into the third quarter before he leaves with a concussion. It’s one of the worst-graded games at the quarterback position in our history that doesn’t feature multiple turnover-worthy throws. Prior to the concussion, Foles simply lost all ability to throw the ball where he wanted.

Foles missed the Eagles’ next game against the Giants before returning in Week 9 to face the Raiders. This time, on his 22 first-half dropbacks, Foles completed 15 for 273 yards and four touchdowns. By the end of the third quarter he tied the single-game touchdown record with seven. He received three negative grades all day in one of the highest-graded games of 2013.

Flash forward to 2015. Now with the St. Louis Rams, Foles makes his debut against a Seahawks defense that is coming off back-to-back Super Bowl appearances. With a receiving corps that features Kenny Britt, Stedman Bailey, Chris Givens, and Tavon Austin, Foles shreds Seattle’s cover-3 scheme for 297 yards on 18-of-27 passing in a 34-31 overtime win. On passes targeted 10-plus yards downfield, Foles is a scintillating 8-of-10 for 197 yards and a score. Four weeks later he completes only 11 passes on 33 dropbacks against the Packers – throwing four picks in the process. By Week 14 he’s benched for good.

Now back to this season, where even in only five starts, Foles has somehow yet again hit similar highs and similar lows. In Week 16 against the Raiders, Foles whiffed on numerous open throws. He had eight simple off-target downgrades to go along with three turnover-worthy throws. This past week against the Vikings, he wasn’t downgraded once. On his 10 pass attempts when faced with pressure, Foles went 7-of-10 for 139 yards and two touchdowns. On his five passes targeted 20-plus yards downfield, Foles went 4-of-5 for 172 yards and two scores. It’s truly a performance for the ages.

Foles has repeatedly demonstrated the ability to play near-flawless football since his second season in the NFL. What we saw Sunday was not a fluke.

The Eagles quarterback can enter a zone the likes of which even “elite” signal-callers are capable. At the same time, he’s hit low points that those same quarterbacks can’t even fathom touching and is liable to do so at a moment’s notice.

He’s unlike anything we’ve ever seen from a grading perspective with his highs and lows. The scary thing for Eagles fans – and Patriots fans at that – is they have no clue which version of Foles will be showing up on Super Bowl Sunday.

Mike Renner is a writer for Pro Football Focus and a contributor to The Washington Post’s NFL coverage.