Williams lunged in on Wigan’s Lee Evans leaving referee Andy Woolmer no option but to give him a straight red.
It was the major talking point of a rather dull affair at the DW Stadium, with neither side showing the cutting edge to force a breakthrough.
Stendel said: “I know Ben Williams wanted to win the ball but he was a second too late and it was a red card.”
The draw leaves Barnsley and Wigan either side of the Championship drop zone going into the international break.
In a cagey affair, neither side offered the 10,214 crowd much to remember.
Wigan goalkeeper David Marshall pulled off two fine saves in a minute to deny Mike Bahre’s thunderbolt and Luke Thomas’s volley in the second half.
The hosts nearly pinched it late on but Joe Garner was denied by Brad Collins from close range.
Stendel added: “We were a little bit better. We can be happy with one point, especially after the last games, it’s good we can get a point from Wigan.
“We have a lot of injuries and had a lot of players playing their first game and the formation was new so we are happy with the point but we had a chance to win it.
“I thought we started well after half-time but gave Wigan more from the game in the last 20 minutes.
“I know we have a lot of new players on the pitch, I know it’s an away game, I know it’s not so easy but we had chances to win and we wanted to play for the three points.
“We had some big chances and if their goalkeeper didn’t play as well, we’d have taken the three points back to Barnsley but he put in a great performance and that made it difficult.”
Wigan manager Paul Cook was delighted his team put an end to their losing streak which had stretched to five games, including their EFL Cup defeat to Stoke.
Cook admitted defeat to Barnsley would have left a dark cloud hanging over them going into the international break. He said: “If we’d lost it would have been the end of the world and that’s what football can be like.
“The positive energy that must come from myself, the staff and the players, we must give the supporters that energy.
“You can see what happens when the lads raise the level, the support comes instantly from the fans and we need to do that more often for them.
Wigan Athletic: Marshall, Byrne, Dunkley, Mulgrew, Robinson, Williams, Morsy, Massey (Evans 80), Lowe, Jacobs (Gelhardt 63), Moore (Garner 63). Unused substitutes: Macleod, Kipre, Jones, Naismith.
Barnsley: Collins, Cavare, Andersen, Halme, Ben Williams, Sibbick, Bahre, Thomas (Styles 90), Wilks (Pinillos 90), Thiam, Chaplin (Schmidt 81). Unused substitutes: Jordan Williams, Walton, Green, Oduor.
Referee: A Woolmer (Northamptonshire).