If you want strength and power then you should squat and deadlift (powerlifting moves and not body building or shaping / conditioning moves). Look up periodization. No drugs, 8 week cycles, once a week on each lift as heavy as you can in the cycle while maintaining your form. Done correctly, you will gain power and speed. I never bought into the single leg anything because you can not lift as much weight, are at a greater risk of injury, and thus delay your progress. You have to be careful to not overdevelop a specific muscle group or you risk injury. Squatting and deadlifting will work all muscles the way the body was designed. Ever wonder why kids pull hamstrings? Typically related to overdevelopment of the quad and not enough development of the hamstring. They are out of balance and one will tear.
Can you provide any evidence that single leg exercises put you at a greater risk of injury? I'd be willing to bet that there is zero evidence out there backing up that claim. Unilateral exercises provide a great benefit and I suggest that all athletes implement single leg training into their programs. In fact, look up some articles by Mike Boyle. He's one of the best minds in the business and he his athletes work almost exclusively with single leg work instead of bilateral leg work.
Baseball is an incredibly asymmetric sport. Unilateral exercises can help balance out asymmetries throughout the body.