Before I tell you why I NEVER include Box Squats in the programs I design for wrestlers I want to start with something else...
Be careful who you take advice from... Just because a guy was a good wrestler doesn't mean he's necessarily a good Strength and Conditioning Coach. He might have bragging rights to winning a lot of matches, but if he's lacking knowledge and experience in how to train wrestlers correctly he may just be giving you the same inefficient program that he used to do. Egos are sometimes the biggest obstacle to a guy becoming a great Strength Coach!
Ok... on to the Box Squats...
Box Squats are a method of performing a Barbell Squat and actually sitting down on to a box or bench, and then blasting back up to a standing position.
Powerlifters have used them for years... in fact, we used to include them in our training as far back as the early 90's... Box Squats are good for Powerlifters who need to develop strength 'out of the hole.'
But Box Squats have now made a re-emergence into the Sports world as the 'new' secret exercise for strength, power and speed.
Unfortunately for those that blindly follow this assumption, this couldn't be further from the truth as it applies to wrestling...
Wrestlers need to have a lot of strength development throughout the core and posterior chain area. This means that the hamstrings MUST be developed in a functional fashion. The Box Squat does just the opposite. When you sit down on a box with a loaded barbell you are actually 'de-activating' the hamstrings, resulting in an 'extension' when rising up from the box. It becomes a quadriceps-dominated exercise when the hamstrings are negated...
Another thing that concerns me is when Box Squats are performed by Youth wrestlers. The Box Squat adds pressure when most youth wrestlers are not strong enough in the core. This can lead to pressure on the spine and injury as well. Youth wrestlers should definitely avoid them.
Now, you could still do Box Squats and then simply perform more isolated resistance exercise for your hamstrings, but then you start working out like a bodybuilder instead of strength training for wrestling.
Another issue I have with using Box Squats for wrestlers is that the cervical vertebrae in the lower back are in a disadvantageous position when you are sitting down into a full squat. This is when they are vulnerable to injury. By resting a weighted load on a bench you are causing undue stress in this Lumbar area.
Simple... Do Pause Squats where instead of sitting down on to a box, you simply squat down and hold in the bottom position for 3 full seconds before rising up to a standing position. This requires you to use a lot more muscle than you would during a box squat too.
The other favorite of mine for wrestlers who want to generate more hip, and posterior chain power is to use a Sumo-Style Deadlift.
Sumo Deadlifts require you to pull with the hands inside the legs which are wider than shoulder width. The back is kept flat, while looking straight ahead. The key to this is to think about tightening up your hamstrings and glutes while lowering yourself to grab the bar. This 'coiling' effect should feel as if you're compressing a spring and getting ready to release it.