The Spaniard equalled his best result of the season with fourth place at the Red Bull Ring while his team-mate Charles Leclerc finished runner-up to dominant victor Max Verstappen.
Sainz had pressured Leclerc for second during the opening stint, but it was agreed that the Ferrari duo would not fight for position.
This pre-race order would come to leave Sainz vulnerable during an early virtual safety that "compromised" his race and cost what he thought to be three places.
By not having track position, Sainz was held behind Leclerc for a delayed Ferrari double-stack pitstop, which meant he was still being serviced when the VSC ended to cancel out some of the advantage.
Sainz explained: "I was very quick on the first and second stint. Obviously, the second stint was already compromised by the first stop, pitting behind Charles and catching the virtual safety car ending, which made me lose six/seven seconds of race time.
"It made me lose positions to cars that I shouldn't have lost, which meant then I had to push on the medium [tyre] to overtake them, get the track limits [penalty].
"My race was compromised from that point onwards. But if I look at the pace, I was very quick out there."
Sainz reckoned that without the strategy blunder, the "shame" that Ferrari did not swap their cars, and incurring a 5s track limits penalty that left him "on fire" with rage, the team would have scored a double podium.
Given the questionable execution of the race from the pitwall and the points lost, Sainz reckoned he would "struggle to see the positives" despite his underlying pace.
He said: "I'm just frustrated. It's been a few races that I have a lot of pace in the car. I wish I could maximise it a bit more because I'm very quick this year, especially in the race.
"I feel like I've done a big step forward... But P4 I guess is not bad, but I think today P2 or P3 was on the cards. Honestly, I'm very happy with my performance today.
"I think I did some very clean, neat moves. I defended well. As soon as I was arriving to one car, I was passing them.
"I was managing my tyres well at the same time that I was attacking. That's why I guess I'm frustrated right now because I struggle to see the positive on this P4 with all the pace and overtaking and defending that I did."
He added: "Clearly I'm in a good moment personally with my with my driving so that's why I guess I'm also frustrated that I'm not maximising the points."
