Toro Rosso technical director James Key reckons the STR11 had the pace to finish on the podium in Monaco and rued traffic in the pit lane which cost Carlos Sainz Jr. valuable time.
Sainz Jr. was running in sixth place behind the Safety Car in wet conditions but lost time during the switch to Intermediate tyres and then the change to dry tyres a handful of laps later.
Sainz Jr. eventually came home in eighth position but Key feels that it should have been possible for the Spaniard to beat Force India's Sergio Perez to third.
"[Carlos'] pace was fantastic, but we had poor pit stops, due to a problem on one corner of the car, which meant we lost track position quite significantly," he said.
"Second stop, we had a similar issue. We just got held in the pit lane with traffic so we lost a load of time.
"In both stops, we lost something like two or three seconds and when you're in a queue of cars, that's the difference between the front of that queue and the back of that queue.
"Had we not had that we would have a Perez-style race because we would have been ahead of this train behind [Nico] Rosberg and [Fernando] Alonso.
"We came away pretty frustrated, because had we got those pit stops much cleaner, we could and should have come out with [Sebastian] Vettel and Perez, preferably ahead because we were ahead of Perez anyway at the beginning of the race and then we would have been in that fight for third.
"Given the pace we had, it could have been quite a genuine fight for third.
"Thanks to that pace, a podium finish was possible, but losing that track position meant it wasn't going to happen. Now, all we can do is look onwards and upwards."