I don't think I've seen an Arsenal side 'turn it on at this stage of the season' for a good ten years now. There's a massive difference between scraping into the top four and going on an 8 game winning streak to claw back a 7 point deficit and win the league.
You also haven't factored Leicester into this theory whatsoever. As niko says, if they win their next four games, it's done anyway.