Dolphins tight end Dustin Keller suffered a season-ending knee injury in Saturday's preseason game after Texans rookie safety D.J. Swearinger went low to make a tackle. It was a perfectly legal play but controversial nonetheless because a player's legs are his livelihood.
For what it's worth (and we'd imagine not much to Keller) Swearinger apologized after the game and offered a defense of his actions.

"With the rules in this era you've got to hit low" Swearinger said. "If I would have hit him high I would have gotten a fine. So I think I made the smartest play. I'm sorry it happened and I pray he has a speedy recovery. ... Right now it's just instinct. You see somebody come across the middle you gotta go low. You're going to cost your team 15 yards. You've got to play within the rules."

Dolphins wide receiver Brian Hartline is unimpressed with Swearinger's rationale for going low.

“It's crap” Hartline told WQAM's The Joe Rose Show (via PFT). ”I mean I think that me personally if you're telling me ‘Oh I'm so worried about going high or hurt[ing] the head' you consciously went low then is what you're trying to tell me.”

Yes that's exactly what Swearinger's trying to tell you Brian.

This was then-Steelers linebacker James Harrison's explanation for hitting Broncos wide receiver Eric Decker low during a wild-card game in Jan. 2012. Decker was injured on the play but Broncos vice president of football operations John Elway conceded that Harrison's tackle was within the rules given the NFL's emphasis on reducing head injuries.