"We're not playing as well as we should do," said McGeechan, whose side face French outfit Castres in Wycombe this weekend before also taking on Leinster in Dublin, followed by a double-header against Edinburgh in December.
"We've shown it in phases but we're not consistent at the moment and we've got to be."
The double-Heineken Cup Champions finished last season in superb form but have already lost to London Irish, Worcester, Northampton, Bath and Gloucester in the Premiership and EDF Energy Cup.
"We're only losing by three or four points but it's the games that we'd want to win by three or four points at the moment that we're not doing.
"It's us having an absolutely clear focus in what makes the difference.
"In Europe, there will be times when coaches and players talk about must-win situations in games and that's what you're trying to get right."