The Pilgrims have won nine of their last 10 league games and are five points clear at the top of League Two.
Last season's beaten play-off finalists beat Yeovil 4-1 on 1 October and have not lost in the league since 13 August.
"I've seen us in training and I've seen us perform and I still think we've got another gear in us," summer signing Bradley told BBC South West.
After last season's disappointment at Wembley, manager Derek Adams added 14 new signings and two more players on loan.
Former Crawley captain Bradley continued: "We're definitely capable of promotion.
"I've been part of different League Two squads up and down the country and I can tell you that if we play to our potential every week, we continue to listen to the manager and take on instructions, then this team is more than capable of automatic promotion.
"I wasn't here last season and don't have any reminders about Wembley and what happened.
"I don't care about that if I'm honest, all I care about is keeping clean sheets and making sure this club is getting where it needs to be. At the minute that's where we are - top of the table and on course for a successful season."
Plymouth Argyle defender Sonny Bradley says the League Two leaders still have better performances in them.