A block by Denver Broncos tight end Julius Thomas against Arizona Cardinals defensive end Calais Campbell has brought up a "dirty play or not" debate, but may be missing a larger point.
On the play in question, the referees threw a flag for a chop block, and the number of the player the penalty was called on belonged to Ryan Clady. The replay showed Thomas actually blocked Campbell, which many people probably thought was a case of the referee misidentifying the player in question.
What actually happened is the referees correctly calling what is defined as a "chop block" under NFL rules, when the average fan might be thinking the penalty was for Thomas blocking Campbell low, particularly when there has been past criticism about such blocks made on defensive players.
Let's first explain what a chop block is: The NFL defines it, in most cases, as two offensive players simultaneously blocking a defender, with one offensive player going high on the other player going low.
There is one exception, which is called the "lure block." It's a type of chop block in which one offensive player acts like he is engaging the defender for a typical pass block (up high with the hands or arms pushing against the defender), only for another offensive player to come in low to block the defender. It matters not if the first offensive player touches the defender -- under NFL rules, it's illegal. This is what happened with Clady and Thomas against Campbell.
So not only were the referees correct to penalize the Broncos on that play, they weren't wrong to name Clady, because he was the player who went to engage Campbell when Thomas came in low.
But that brings up a bigger issue: Let's say Clady does not move toward Campbell, indicating a block attempt, and Campbell decides to go around Clady. Thomas then comes in low on Campbell low, where Campbell sees him coming, and Thomas hits Campbell below the knee.
In that case, Thomas is engaging in a cut block. However, it's a version that is not illegal under NFL rules. One needs to keep in mind that cut blocking is simply the tactic of blocking a defender at or below the knee, without having another player engage the defender up high. (In other words, cut blocking does not equal chop blocking under NFL rules.)
Cut blocking is a tactic that former Denver Broncos coach Mike Shanahan was often criticized for utilizing because some coaches, players and fans considered it dirty. However, because the NFL has never made cut blocking in general illegal, players and coaches on many teams have utilized the tactic. And that raises a larger issue worth considering: Ensuring the safety of defenders trying to make plays.
A few years ago, the NFL modified its rule regarding defenders hitting quarterbacks in the knee or below, prohibiting a defender on the ground who isn't bocked or fouled directly into the quarterback from lunging or diving at the quarterback's lower legs. The change came about after the 2008 season, in which Tom Brady tore his ACL and MCL after Kansas City Chiefs safety Bernard Pollard dove into Brady's knee, after Pollard had been blocked to the ground by Patriots running back Sammy Morris.
The question we should ask, though, is if we believe quarterbacks should be protected from such shots to the knee or below, should we not do the same for defensive players who are attempting to rush the passer or track down a running back?
It may be time for the NFL to implement a rule that makes it illegal for offensive players to block defenders at or below the knees within five yards of the line of scrimmage. That would force offensive players to block by more "traditional" means and do a lot to protect defensive players from injuries.