I believe it was Dan John who emphasized hamstring tension for many althletic movements, and coming out of a stance is no exception. This implies that technique is more important than additional muscular strength, but once you get that down, how do you best work this type of strength? With hip flexion exercises like SL DL's, RDL's, good mornings, ghr's, etc.
I've never played football on a team, or on a regular basis. So? What point does this make other than show that you think yourself at a greater authority, or are immune to any crtiticism I should have? If you have any other qualifications, please feel free to list them. Squats activate everything leg presses do, and then some. EVEN IF squatting didn't help with explosiveness (it does), to only limit a workout in the effort to make you come out of your stance faster is stupid. Squats will give you power pretty much every second after you leave your stance.
And for the record, you've contradicted yourself.
If hip flexion is key to generating more power coming out of a stance, and leg presses work hip flexion, and squats work everything leg presses do and more, then squats should therefore be beneficial to coming out of the stance.