In addition to the reads being different lateral movement is critical for inside versus downfield movement from OLB. Urlacher had phenomenal speed and range from sideline to sideline, which when combined with his ability to diagnose and react quickly, and communicate effectively served him quite well in his years. Then you have players like Bostic who can get good lateral movement but couldn't make a read. I think Jonathan Bostic is what the child of Brian Urlacher and Paris Hilton would have been; all the physical tools but unable to read A Dr. Seuss book.
Being able to make the reads is still the most important part of the position I can't remember the guys names off the top of my head now but there are several current examples of MLB with less than optimal lateral speed and agility, but they make up for it by being able to make the read much quicker. Ideally you would have all The above skill sets in addition to size, coverage ability,and still being able to effectively rush the passer when things need to be shaken up, but players with the full package tend to be rare, they rate as rare as Phil Emery would say.
