[Valdarez]

Clutch is a situational bonus (temporary boost) that affects multiple attributes for the given player. Stamina is a bonus that affects the players overall performance. It's drained as the player is on the field, and replenishes while they are off the field (benched). Stamina bonus is probably better for an HB who is grinding out the ball over and over again, where as Clutch is going to be better for a WR / QB.

Workhorse allows a player to get better as the game goes along. Their natural attributes will begin to get a slight bonus later in the game if they have had enough carries (unknown threshold). Where Stamina keeps your natural abilities close to their peak, and clutch gives you a temporary boost to your peak values, work horse will permanently raise those peak values for the duration of the game.

Strength seems to make a players natural abilities better. For HBs they tend to break more tackles, for QBs they get a little more distance (not a lot guys, but a little), for WRs they are better at breaking coverage (bump) and running routes / catching balls in traffic.

Branching Tackles is an ability that allows a player to break tackles by press the 'A' button. With Strength, you may knock a guy over without ever having to press A. I personally will always take Strength Bonus over Branching Tackles.