That's a terrible comparison. The Nationals were never even close to THIS good, THIS late in the season. Furthermore, even when the were 10 or so games over .500, they had a NEGATIVE run differential. Anyone with half a brain knew they were going to eventually suck.
The Tigers lead MLB in RD this year. I'm sick of people making dumb comparisons. They aren't a fluke. BP has them at over 80% odds to make the playoffs. Before you scream, the Sox are at 76% odds. Take that with a grain of salt, but historically, teams this good record wise and RD wise don't miss that playoffs that often.