Scouting Tackles: What to look for
You could make the argument that, other than quarterback, the left tackle position in the most important on the field for an offense -- mainly because the left tackle (or right tackle for lefty QBs) is the number one protector for the quarterback.
There are three basic requirements for an offensive tackle in the NFL and this is primarily what scouts are looking at when evaluating tackles in college:
1. SIZE: The minimum size ideally is 6'5" with at least 33 inch arms.
2. TOUGHNESS: Play physical and finish the play with toughness, playing all the way to the whistle.
3. ATHLETIC ABIILITY: Must show ability to slide laterlaly and adjust to movement.
See the video above for examples of all three from Texas A&M's Jake Matthews and Luke Joekel, as well as Michigan's Taylor Lewan.