The teams were deadlocked at 12 points each at half-time but the visitors failed to add to their tally after the break, while Horsham added three tries, one of which was converted.
Wiggins admitted his side’s failure to push on in the second half was disappointing but said it was not down to any lack of effort on their part.
The head coach said: “We thought the game was there to be won at half-time but it did not happen for us in the second half. We didn’t perform and they came back out stronger than we did.
“We went off the boil a little bit and they took their chances. The better team won but I was pleased with how we defended.
“We held them up over the line three times, once in the first half and twice in the second which is no mean feat.”
Adam Michael and Luke Armstrong scored Deal’s tries in the first half – both of them as a result of good handling – with Matt Halpin adding a conversion but Horsham never looked back after grabbing their third try just two minutes after the restart.
Injuries in the final quarter to backs Jack Browne and Armstrong didn’t help Deal but Wiggins was pleased with the way his team and in particular, the forwards, stuck to their task.
He added: “They had a much bigger pack than us and we were in trouble for the first 15 minutes but then all of a sudden we produced the scrum of the day and whacked them off their own ball and we had parity with them in the scrums after
that.”