The Robins made a good start when Andy Procter scored an own goal in the third minute, but the hosts soon recovered with three goals in the space of eight minutes.
Danny Mayor claimed the first, letting rip with a 30-yard thunderbolt that found the top corner of the net in the ninth minute.
Procter made amends for his earlier slip-up be heading home Craig Jones' corner to give his side a 12th-minute lead.
Then Nathan Cameron got on the end of a Jones cross in the 17th minute to make it 3-1. Substitute Jessy Reindorf completed the rout by heading home from Mayor's cross in the 76th minute.
"It wasn't good enough," said Yates. "We made a good start and looked alright but then conceded three goals in eight minutes so it wasn't good enough.
"We need to go back to the drawing board and start again. We need to find our identity because we're getting beaten at both ends of the pitch and conceding too many goals.
"They were a threat and looked a strong outfit but the goals were too easy and it could've been more.
"The players know it's not good enough, they didn't need me to tell them that. At both ends of the pitch we're not anywhere near where we should be.
"The games are coming thick and fast and you want that to put it right. Whoever plays on Tuesday (against Plymouth in the Johnstone's Paint Trophy) has a massive opportunity to stake a claim because no-one is doing that at the minute.
"It's up to them to say 'that shirt's mine'."