Sinclair, who grabbed his second goal of the season with a superb first-half strike, was disappointed as his side went on to conceded three second-half goals to slip to another dismal defeat.
The 31-year-old, who joined captain James Clarke in moving from Bristol Rovers to Walsall in the summer, went on to admit that the team have to be able to concentrate for the full length of games and begin to put contests to bed.
Speaking via the Express & Star, Stuart said; "It was a game of two halves, but the game isn’t 45 minutes.
"We have to concentrate and do more for 95 minutes and we’re not doing that at the minute and we need to do it next Saturday. We’re here for 95 minutes and not 45 so it doesn’t mean anything, it’s frustrating.
"We need to start coming together now and start putting demands on ourselves and making sure every game we’re at it, we can’t carry on, we need to do more."
The Houghton Conquest-born midfielder has made fourteen first-team appearances so far this season and went on to praise the Saddlers faithful for their passionate support, with over 850 making the trip to Brisbane Road, despite recent results.
He added; "It’s been fantastic home and away, the passion they show is unbelievable – and that’s why it’s frustrating because in the first half we’re pushing forward, but the second half is so disappointing and it was shown in us and in the fans.
"That’s why this club can move forwards because it has such passion and we need to make sure we produce that on the pitch. Of course you do. From now until Saturday you’re disappointed, it’s your life so of course it affects you."