The Australian dropped two places at the start of Sunday’s race, falling to 11th from ninth on the grid.
Team-mate Yuki Tsunoda also fell back, completing the opening lap in Imola ninth after starting seventh.
Ricciardo lost places to Sergio Perez, who’d qualified out of position in 11th, and Nico Hulkenberg who started 10th.
Hulkenberg finding a way through was especially painful as, in clean air, Ricciardo felt he had more pace than the Haas.
But with overtaking near impossible in Imola, he found himself stuck in the opening stint, which had a significant impact on his race.
“I think it looks very different if we get a better start,” he opined.
“The laps we have in clear air, we show some pace.
“I feel like in clear air, we probably had a tenth, maybe two, on Hulkenberg.”
Ricciardo started on the medium tyres, boxing on Lap 11 for a set of hards as he looked to undercut Hulkenberg.
Haas reacted two laps later, the German maintaining the place ahead of the RB.
Once the pit cycle had been completed, Ricciardo found himself 11th before losing out to Lance Stroll and, on the final lap, Kevin Magnussen.
“I think they just had an alternate strategy,” Ricciardo said of losing out to the Dane.
“It’s another place where he was already ahead of me braking into Turn 1.
“When I was behind Sargeant in the middle of the race, obviously we were a lot quicker but I was never even alongside into braking into Turn 1.
“Maybe Kevin had a bit of tyre delta, I don’t know, but following, we feel like people are able to overtake us a little easier that we’re able to overtake them.”
The hard tyres Ricciardo used in the second stint also didn’t give the Australian the feeling he was after, adding further complexity to the latter half of his race.
“As soon as I left the box, I didn’t really feel like I had a great peak on the tyres,” he explained.
“I didn’t feel the balance was great but nonetheless they still felt like we had an ability to lap decent, compared to our rivals.
“But the starts, they’re hurting us at the moment,” he added.
“I don’t know yet what the issue was – I didn’t feel like I botched it; it felt like everything was going okay from the procedure.
“It’s so sensitive and something we’re working on.
“Today, obviously, it cost us. I think if we stayed in front of Hulkenberg at the start, Yuki and I go off together, then a completely different looking race.”
Tsunoda salvaged a single point as he finished 10th, taking RB’s season total to 20 from the opening seven races – the Japanese driver having contributed 15 of those.