Originally Posted by EddieMilner
Speed (here me out).
A speed guy can get to more balls in the field.
A speed guy can steal bases more aptly to advance a runner.
A speed guy is more likely to score on a base hit.
You can work on a lot of things in baseball, but being able to run a 40 in 4.4 is god given.
It is not that important of a skill. Speed alone will never give someone a career in MLB. See: a lot of guys that run 4.38 40's that never made it. The ability to hit 40 HR's is a lot more important than being fast (although that isn't my #1 important skill). Kenny Lewis comes to mind. He was the fastest player in college football when he was going to play at Virgina Tech, he signed with the Reds though and failed without showing any prospect of being good. Stole 71 bases in 3 seasons and had a career OPS of .644.
When evaluating tools, speed is probably fourth out of the big five, unless you have a cannon of an arm, it could be your 5th most important tool.