So says ESPN:

Across five games in six weeks, we’ve seen the full gamut of Nick Foles appearances. On Christmas, we saw the Foles who washed out in St. Louis under Jeff Fisher. On Sunday, we saw the guy who had one of the hottest half-seasons in league history under Chip Kelly in 2013. So how did the Eagles turn their quarterback around? And is there an early guess on which Foles we’re likely to see against the Patriots in Super Bowl LII? I ran the numbers and watched every Foles snap from those five starts to try to identify the differences between Good Nick and Bad Nick:

http://www.espn.com/nfl/story/_/page/Barnwellx180122/2017-nfl-playoffs-mystery-philadelphia-eagles-quarterback-nick-foles