The Saddlers have now lost three games in a row over the festive period following their 2-0 defeat to Carlisle on Saturday.
Before that, they were the in-form side in the division with four consecutive victories launching them into play-off contention.
Despite the loss of form, Walsall are still within four points of the top seven and have an opportunity to challenge.
When asked what causes the team’s inconsistency, Sinclair said: “I think it’s a mixture of things.
“We have a young side and for a lot of the guys, it’s probably their first season where they’ve played a lot of games.
“I think we are growing as a side and we are becoming stronger.
“It’s that little bit of time, making mistakes on the pitch and understanding the next game I don’t do that and I develop.
“We’ll try and push forwards in that respect.
“I think the most important thing is for us to go away and make sure when we come back that we’re pushing forwards.
“If we can put a run together and be consistent then we’ve got a chance.”
Walsall have made a habit of going behind in games this season as they often concede the first goal.
For Sinclair, that pattern needs to be broken.
“You’re already on the back foot and probably even more so at home,” he added.
“It’s even more important, so that’s something we’re going to have to work on and make sure we’re better at in the second half of the season.”
The 3-0 loss to Cheltenham on November 21 is widely regarded as Walsall’s worst performance of the season so far.
But manager Darrell Clarke believes the display against Carlisle was on par.
“This and Cheltenham are shockers,” he said.
“Really bad performances that are nowhere near the standard that we set ourselves.
“They’re an honest bunch of lads and they know they were miles off it.
“All I can do now, myself and my staff, is get working away with the players, which we will do. That’s what we’re about.
“Making sure that when we come back in a couple weeks against Oldham that we’re a hell of a lot better.”