The 28-year-old joined Paolo Di Canio's men in the summer after leaving Huddersfield but since returning from a calf injury has struggled to nail down a first-team place.
"I think I'm my own biggest critic and I know I've been below-par personally," he told the Swindon Advertiser. "To see I'm out of the side, I think, is deserved because I don't think I've done enough to stay in the team and get in the team.
"I haven't scored enough goals, I haven't played well consistently, I've had decent little spells in games but that's it.
"I try to tell myself that but hopefully the tide will turn and I can put in some good performances for the club and try to show why the manager brought me here and win some fans over.
"I've got half a season to put things right to prove to myself and prove to the manager that I'm good enough to play for the team."