Against the Championship side, Rodriguez was played in his preferred role as central striker and shone in a much-changed Saints side, scoring his first goals for the club in their 2-0 defeat of Wednesday.
"He had a massive impact," assistant Crosby said. "I thought his movement was excellent against two centre-halves that perhaps wanted him to come short.
"I thought his movement in between and down the side of them was really good.
"He is one of many players who have taken their opportunity.
"He has had to bide his time and wait for his chance but he has been a great character around the place and wants to improve.
"He is at a good age for the club and has taken his opportunity.
"We know he is most comfortable in a central role but he has good competition in front of him at the moment.
"Whenever you get an opportunity, you've got to take it and he did that tonight. Whenever he is needed, we know he is more than ready."