Yeah, I found it myself after about another 2 minutes of digging.
Anyway, the gorilla in the room seems to be the BABIP. Nava's BABIP has gone back up to around .340, which seems high to people because it's well above the league average. It's the biggest weapon in the arsenal of those concerned that Nava is a fluke.
Food for thought: Nava's BABIP has been consistent throughout his minor league career. His BABIP average over his mL career was .337, well within the margin of error of his current .344 in the bigs. He's a line drive hitter who can really put some good swings on the ball, and tends produce a lot of sharp contact. That will generate more hits than the average when contact is made.
He has a power swing for such a small player, a lot of bat speed to make up for his lack of being physically built. Thus the line drives. And he strikes out a bit from swinging hard to hit those drives, which increases the BABIP a bit on the other end. And we've all seen him hit some screamers. He's been Laser Show, Jr. from time to time. So the BABIP isn't relly something that concerns me. It might normalize, or this might BE his normal BABIP. We don't know yet.
As for power: Nava's power is mostly in low line drives, and he can get it to the wall in a hurry from time to time. If Nava ever found a way to change his swing just a little and get under the ball just that one tiny fraction of an inch more, like Pedroia did, the home runs could come for him like it did for Pedroia. I dunno if it'll happen, but the skill is there to make it a possibility if he can make the right adjustments.
That said? Nava is probably a little bit of a fluke. For his career. whatever he gets of it in the bigs he's going to be closer to .270/.380/.420 than his current line. I don't think he's going to continue being one of the league's best top of the order hitters from now to retirement, in other words. I still take that line in the 2 hole over most of the league's #2 hitters.