When Chicago released DT Tank Johnson, I thought it was a huge blow to them, but down in the comments my fellow SB Nation and Chicago Bears blogger disagreed. Although his comments on my site were respectful, I felt this harsh post regarding brain size might just be directed at me. I feel the need to respond.
Depth at defensive tackle is very important, even if the players providing that depth don't seem all that important to the overall defense. If the tackles can't hold the line at the point of attack, then the run defense is a big problem. Only after DT Corey Williams became the starting tackle alongside DT Ryan Pickett last season did they have quality starters, the best since 2000 when DTs Russell Maryland and Santana Dotson started and DT Cletidus Hunt was the top backup. In 2001, DTs Dotson and Jim Flanagan's were running on the fumes of their careers and Football Outsiders ranked their defensive line 20th by Power and 28th by Stuffed. Power ranking is when the opponent will gain 2 or less yards on 3rd or 4th down, while stuffed ranking is gaining zero or negative yards on 1st down or less than one-quarter of the yards needed on 2nd down or later. Basically they couldn't stop the other team when they really needed it. They improved in 2002 to Power 8th and Stuffed 17th because DE Vonnie Holliday and Hunt were playing for contracts. The adjusted yards per carry dropped substantially overall not because of the defensive line in 2002, but because they opted to start LB Hardy Nickerson instead of a real, living middle linebacker. After Holliday went to Kansas City and Hunt took the rest of his career off, they fell apart in 2003 to 29th Power and 17th Stuffed. It could have been a lot worse, but they received a gift when New Orleans released NT Grady Jackson. Jackson was outstanding for the remainder of that season and made those overall 2003 numbers respectable, but when Jackson started getting hurt and overweight in 2004 and 2005, there was no depth to back him up and the numbers aren't good in those seasons. They haven't had an above average run stopping defensive line since 2000 and that is why drafting DT Justin Harrell was a good idea because he gives them better depth at defensive tackle then they have had in many seasons.
Since 2001, while the Packers have struggled, Chicago has usually done a pretty good job with their defensive tackles. After a poor 2000 season, they signed free agent DTs Ted Washington and Keith Traylor in 2001 and the defensive line improved to Power 3rd and Stuffed 7th. When Washington was hurt during 2002, they slipped to Power 4th and Stuffed 12th. After Washington left for Oakland in 2003 and Chicago was forced to rely on too much DT Bryan Robinson, they fell to Power 25th and Stuffed 19th. In the first draft for new coach Lovie Smith, he was given DTs Tommie Harris in the 1st round and Tank Johnson in the 2nd round. In 2004 and 2005, DT Ian Scott started alongside Harris while Johnson played in every game as the top backup and they improved to Power 17th and Stuffed 3rd in 2004 and Power 11th and Stuffed 4th in 2005. They remained consistent in 2006 at Power 15th and Stuffed 2nd although Harris missed the end of the season and Johnson began to start ahead of Scott. Now they enter 2007 with Harris recovering from his injury, Scott in Philadelphia, and Johnson in the unemployment line, but they didn't add any defensive tackles in the draft. The only free agent addition, and likely starter alongside Harris, was DT Anthony Adams who didn't even start in San Francisco on a poor defensive line.
Chicago has had a good and consistent defensive tackle rotation over the last three seasons, but that was blown apart. The Packers have had to watch practice squad guys like DT Colin Cole receive substantial playing time over the few seasons and now it is Chicago's turn. Bears fans won't realize how good they've had it until they get to watch their defensive line replacements struggle on the field in 2007.