Hoo boy, this episode.
After failing to save poor innocent Rickon Stark from getting brutally shot by Ramsay Snow, Jon's pissed off enough to say "screw it" and faces the oncoming Bolton cavalry on foot, all by himself. He seems prepared to die (again), and at the last possible second, his soldiers crash into the oncoming hordes and keep their commander from being squashed.
THEN, after kicking more than a little ass, Jon finds himself getting trampled underfoot as his army is flanked by the Boltons. Sure, this isn't exactly great luck, but it could be argued that by being kept inside the terrified masses of his own men, Jon was actually kept from getting exposed to the oncoming Boltons.
AND THEN, after he pulls himself up and out and comes to realize that everything is pretty much lost, the Knights of the Vale arrive to everyone's surprise (except anyone who's been paying attention to what Sansa's been up to) and kick the crap out of the Boltons, leaving Jon time to go punch the crap out of Ramsay. Huzzah!
So what does it all mean? Perhaps Jon Snow is simply always in the right place at the right time. Perhaps Melisandre is onto something, and the Lord of Light has bigger plans for him in the end. Perhaps we'll soon learn more about his origins and why he might have a much bigger role in how the Game of Thrones ends. Only time will tell.