The 31-year-old claimed the third podium finish for Trek-Segafredo since claiming the opening team time trial, with Marianne Vos (CCC-Liv) securing her second 2020 Giro Rosa stage win.
“I think our best tactic with Trek-Segafredo is always teamwork," Deignan said.
"We thought it would maybe be windy (during Stage 5), but we were unfortunate that it wasn’t.
"We have a really strong team. Elisa (Longo) is well placed on the GC and we’ll continue to have an open and aggressive tactic.”
After Monday night's (AEST) monster 180km Stage 4, the peloton could have been forgiven for hoping for a slightly flatter run.
However, the category 2 climb of Madonna della Civita and the category 3 Monte San Biagio were the major obstacles of the stage with the sprinters having to negotiate the difficulties of the ascents if they wanted the chance to win the flat run-in to Terracina.
Ultimately it was Vos who claimed her second stage win of the race from a bunch kick, with young Belgian Lotte Kopecky (Lotto-Soudal) finishing second and Deignan in third.
"I have to say that I already have good memories here and it was not an easy stage with the climb," Vos said.
"We tried to make it hard for the other teams, so the team did a hard pace on the climb and split the field.
"It worked out a little but it wasn't easy to get there to the front. But they did a great job and put me in a good position."
The daily highlights show from the Giro Rosa screens daily from 4pm on SBS and streaming on SBS On Demand.