Despite his forecast, the Geordie boss saw his team hold the National League South table toppers to a 2-2 draw on Saturday.
The Glovers have a seven-point lead but the Darts will be in the promotion mix too when it matters, he feels.
Dowson maintains his team will finish in the play-off places despite currently sitting 12th and praised his side for their fighting spirit as they became only the third club to take points off the leaders since early September.
“The reason they are top of the league and the reason they’ll win the league is because they make less mistakes than everyone else,” the manager said.
“If we weren’t making the mistakes, we’d be in the top three at the minute. We’ve got some good players in there, and they’re a good defensive unit, but it’s the mistakes we make at times.
“We did well, we showed our battling qualities, but it’s another game we’ve got to score three times to win.”
He told the club’s video player that he still think they’ll be there when crunch time arrives, adding: “I’ve always said that we’ll finish in the top seven at the end of the season and we’ll have a go from there, and I still believe it.
“We’re unbeaten against some good sides but we’ve got to cut out some silly mistakes.
“The new signings we’ve made recently have been outstanding, we’ve just got to get in some more like that who will improve things. As a manager you’ve got to live and die by the signings, and some haven’t worked out.”