tackles are a funny statistic. Each NFL team hires a crew to record game tackle stats for home games. The numbers they come up with are submitted to the league as "official." Then after the game, with the exception of a few teams, the coaching staffs review the game footage and submit their own tackle stats to the league, and they are considered to be the "official" numbers. As recently as 2008, Oakland, Miami, Houston, and Seattle were the only teams not to do this. The problem is that there is no consistency on what constitutes a tackle from team to team. Players have seen huge jumps and dips in their recorded tackles, and there have been cases where teams have reported impossible stats. (like recording more solo tackles than available defensive plays)
I'm not trying to discount Rubin's value. Just pointing out that tackle stats are a good guess at best.