And with both Toulouse and Quins having won two from two, Redpath knows qualification is no longer in Gloucester's own hands.
"It's very tough to qualify now. You don't usually lose at home and go through," said Redpath, after Gloucester failed to build on a hugely encouraging performance in France in Round 1.
"You've got to get a minimum of four, if not five wins to go through. We knew that if we wanted to proceed in the tournament, we had to win this one.
"The fact that we didn't, and we didn't get any points from it at all, means we're going to struggle."
Gloucester dominated territory and possession against a Quins team unbeaten in 11 previous matches in all competitions but they were always behind on the scoreboard.
Outscored by three tries to nil and comfortably beaten in the end, Redpath was left to bemoan an array of chances that went begging in the West Country.
"We created opportunities and didn't take them. Credit to Quins, they had three chances and took three," added Redpath.
"You're not going to win many games unless you get those percentages higher. If you create but don't take, you get punished.
"We were second best on many things. Our basic control of possession was poor at times. We didn't look after the ball well enough, we didn't deal with the contact area well enough and we lost the game.
"It was unlike us in some parts. You need to have composure in games like that and we didn't. Quins' decision-making was better than ours, their control was better than us and they deserved to win.
"We didn't function at the level needed to be competitive enough. We cant hide from that - we have to accept the criticism."