You can have great vision, but if you lack the strength and size, you are going to be ineffective as a linebacker to say the least.
Not only do great linebackers put themselves in advantageous positions, they also use their speed and size to finish off the play.
Great linebackers are like freight trains—big, hard-hitting and they come at you fast.
Linebackers are often smaller than offensive linemen, but their speed in comparison is much better, which allows them to erase any disadvantages.
For example, center Jeff Saturday is 6'2" and 295 pounds. Linebacker Ray Lewis is 6'1" and 250 lbs.
There is a difference of 40 pounds, but when Lewis builds a head of steam and bull-rushes Saturday, I would say the advantage is in Lewis's favor.
Linebackers have to be big if they want to be game changers. Not only that, they need some speed.
I'm not talking about 40-yard dash times; if you are in the NFL, you can sprint. Whether or not your positions demands that you sprint all the time is a different story.
The best test for a linebacker's speed is the three-cone drill. The ability to change direction quickly, pick up your feet and change speeds is extremely important for linebackers so they can avoid broken plays and mismatches.
Linebackers are going to be big and strong; whether or not they have the right speed to use their size is a different issue entirely.