The game was held up for four minutes following an incident around the sending off.
It started with Wrexham's Chris Llewellyn making a two-footed tackle on Stefan Oakes.
Wrexham's Lee McEvilly and Wycombe's Anthony Grant were booked before Baptista whacked the ball from close range into the stand full of home supporters.
Stewards had to intervene to calm the crowd and the referee's assistant went on the pitch to help restore order.
Wrexham started brightly and might have had an early goal when Marc Williams had a good chance from a free-kick that went straight to the keeper.
Grant had Wycombe's first chance on goal with a header saved by keeper Michael Ingham, who was spared the trouble of another save when Matt Bloomfield shot straight at defender Steve Evans.
Michael Williamson headed Wycombe into the lead when he finished in style after Oakes clipped a free-kick to the near post.
Soon after, Jermaine Easter might have added a second but mis-kicked when only six yards out.
Wycombe were getting on top and Ingham raced out of his area to deny Bloomfield before Easter missed another chance shooting wide from the edge of the area.
Wrexham's Williams might have levelled on the stroke of half-time from their only real opening of the first half for the Red Dragons but he volleyed well wide from Llewellyn's cross.
Wrexham sent on the burly McEvilly for the second half and his arrival gave them a good target in the box which they had been lacking in the opening period.
Yet it was Wycombe who then scored with Easter notching his 21st goal of the season.
Grant crossed, Tommy Mooney flicked on against the underside of the bar and the ball dropped for Easter to hook in from barely a yard out.
Bloomfield should have added a third goal but his shot came back off the far post soon afterwards.
Follwing Baptista's red card, Wanderers sacrificed their leading scorer Easter to send on reserve keeper Jamie Young.
The incident sparked a lively reaction from the crowd which spurred the home side to greater efforts.
Danny Williams shot wide from a Ryan Valentine free-kick and a McEvilly shot was blocked by Williamson at close range.
Wrexham lost their will to fight as they crumbled to their second home defeat in a week and ten-man Wycombe took the points.