Rumors have been running rampant that the San Diego Chargers intend to switch from a power-blocking scheme to a zone-blocking scheme for their offensive line since the hiring of Joe D'Alessandris. Why? Well, D'Alessandris ran a zone-blocking scheme with the Buffalo Bills after running it for years at Georgia Tech. Considering that neither of D'Alessandris' bosses have any experience with coaching the offensive line, I can't imagine that he was brought to San Diego to learn how to run the power-blocking system that the team used under Hal Hunter and Norv Turner. I have a very basic understanding of the differences in Power Blocking Schemes (PBS) and Zone Blocking Schemes (ZBS), but it does seem comparable to the differences between a 4-3 defense and a 3-4 defense. The 3-4 defense relies heavily on coaching, working to confuse opposing offenses rather than try and beat them with skill. This takes some of the burden off of the General Manager to put above-average athletes at every position. The 4-3 defense requires good coaching and smart players, but it can not be effectively run without great talent at just about every position. PBS is just what you would think. Five offensive linemen walk up to the line of scrimmage with a plan. They each have a guy that they have to block. On a running play, they each have a guy they need to push back. Teams with outstanding power along the offensive line (such as the San Francisco 49ers) can run this scheme without issues and reap huge benefits from it.