The phrase in question is
"This allows his arms to naturally accelerate through the bottom of his swing and unleashes a lot of power on the ball."
My question is about the proper tense of the verb, "unleashes". I'm unsure if it's supposed to match the verb "allows", as in "this allows... this unleashes", or the verb "accelerate", as in "his arms accelerate... his arms unleash".
Either way illustrates the point I'm trying to make.
I suppose the verb tenses are clear if the sentence didn't start with "This". It could be rewritten as "His arms accelerate... and unleash...".
I wanted to start this sentence with "This" to refer to the point I made in the sentence before.