Watson was expected to be available for last week's clash with Adelaide after straining his hamstring in Essendon's round 14 loss to Hawthorn, but was left out of the team.
His absence for a further week cast doubt over his rehabilitation from the injury, but Hird said the club was just taking a conservative approach.
""Jobe actually ran flat out on Wednesday and trained pretty much fully, and just didn’t feel quite right,"" Hird said from Windy Hill on Friday.
""I wouldn't even say it was a setback.
""The game is at the point now where the ability to rotate isn’t as great as it [was] and guys spend a bit more time out on the ground, and we're just not prepared to take a risk with Jobe, as big a game as this is for us.""
Watson first injured his right hamstring in round eight when the Bombers played the Brisbane Lions at the Gabba. He missed three weeks to return in round 12, only to injure his other hamstring against the Hawks.
Hird, however, said there was no anxiety at the club that the injury would trouble the brilliant on-baller for the rest of the season.
""There's always a concern when your best player and captain gets injured and you hope they get better as quickly as possible, but there is no reason why it will linger,"" Hird said.
""The interesting thing was that we almost played him last week in Adelaide. We had him picked on Wednesday and then sort of got cold feet with the cold night and going over to Adelaide, so he's almost played two weeks in a row.
""But four weeks with a hamstring means he should definitely be right next week,"" he said.
Despite winning three games in a row and having an excellent recent record against the Blues - Essendon has only lost one of their past eight match-ups - the Bombers' task of continuing that record has been made harder with the loss of tough midfielder Heath Hocking with a foot injury.
Hird said Hocking, who finished runner-up to Watson in last year's best and fairest, would benefit from the break.
""We think it's only (going to keep him out for) a couple of weeks. It's a stir up of an old injury,"" Hird said.
""If it was the end of the year and you had one game to go, you'd keep him going, but we think by giving him a couple of weeks rest the heat will go out of his foot and he'll be right to play in a couple of weeks.""
Ben Howlett, who was subbed out of last week's game with the Crows at half-time, is considered a 95 per cent chance to play on Saturday, and Hird said that Michael Hurley, although missing the club's main training session this week, was fit to play.
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