The rookie out-half's defending has been the subject of scrutiny in his debut Six Nations, and it’s something Wales exploited last time out in Cardiff when the 22-year-old got caught wrong-footed in the build-up to Tom Rogers’s try just after half time.
That defence is going to be further tested by a French side that have scored 21 tries and 141 points in just three games, combining a blistering backline with a bruising pack of forwards, which they have also supplemented with a 7:1 bench split.
And while Easterby admits the Leinster 10 does have to add to his defensive game, he’s backing him to stand up to Les Bleus on Saturday.
"He's fully aware of the need for him to step up in that area and I'm sure we'll see a physical side to Sam on the weekend that will maybe put a few of the question marks to bed," the Ireland interim head coach said on Thursday.
Prendergast’s 15 missed tackles ranks highest in the championship, but Easterby (below) believes it’s an element of his game that will get better with experience.
"I guess it's an area of the game which every player has to have time for, in terms of preparation, the physical battles of the game.
"I think at times he's been excellent, and he's put some real good shots in and at times he's missed a couple, and it's important that he's working incredibly hard at figuring lots of things out in his game, trying to be the best number 10 that he can be, best number 10 that can create opportunities for the team on the attack.
"But he also understands and values the other side of the ball, and that's kind of part and parcel of his growth as a player, making sure that he understands how important both sides of the ball are.
"And we certainly have had conversations around it across the championship, not just after the Wales game."
A win for Ireland on Saturday would leave them within reach of an unprecedented third men’s Six Nations title in a row, and also on course for a second Grand Slam in three years.
Ireland have won the last two meetings of the sides, both of which were their best all-round performances of those championships.
While they have won three from three in 2025, there still appears to be plenty of room for improvement, with periods in each of those games where they have either started slow or had dips in momentum.
And Easterby says they are still chasing that complete performance.
"That would be what the team is always striving for: consistency and not too many dips in momentum.
"I guess the pleasing thing is we came from behind against England, found a way in the second half to take the game away from them.
"We started really well in Scotland and, even though the scoreboard probably didn't reflect that, we felt like we were dominant. And even when Finn Russell and Darcy Graham went off, we felt like we were probably the more dominant team in that first 20, 25 minutes.
"Against Wales, again we probably didn't feel like we'd taken as much of those opportunities early on, but we felt dominant. We went behind and we came back.
"There's been different elements of the game where we've won and lost momentum. I guess our challenge is to try and build as much momentum and build big moments on big moments on big moments. That's when you start to get the return, the reward."
Ireland had a record win against France in 2024, but crucially Fabien Galthie’s side were without the best player in the world, Antoine Dupont (above), as well out-half Romain Ntamack.
The Toulouse half-backs start on Saturday for the French.
"I think physical fitness [will be crucial] but mental fitness is really important, having the ability to stay in the game continuously until there's a break in play and then you get that chance to take a breath.
"Likewise, for them against us, they'll feel the same probably with Jamison [Gibson-Park] that they'll have to be on it all the time and there's no difference for us against someone like Antoine Dupont.
"I think they certainly wouldn't always stick to script and there would be an element of unpredictability around the way the game.
"Ntamack, he's probably a lot bigger than people consider. When you see him on the TV, he's actually got a big stature and he has the ability to play the game with his Toulouse team-mate [Dupont]and that sometimes gives them an advantage as a team.
"That sometimes gives them an advantage as a team but he's kind of got an all-court game in terms of his kicking, his ability at the line, his ability in his passing game.
"But we've got a couple of pretty special ones there ourselves, haven't we, in Sam and Jack Crowley?" he added.
