Tommy Bowe leaps to defence of Ireland team-mate Jared Payne
Ex-Ulster and Scotland boss Williams claimed Ireland have "huge issues" in midfield when analysing the 44-10 victory over Romania for Irish channel TV3.
Williams believes Ireland will struggle to reach the latter stages of the tournament with Payne at 13 - leading Bowe to stick up for his Ulster team-mate.
Bowe branded Williams a "bad cop" pundit, insisting Ireland would take little notice of outside opinion.
"I was just chatting to one of the lads yesterday about how good it is to actually play alongside Jared," said Bowe.
"As a squad, we know what a talented player Jared is.
"He has a lot of time on the ball and he makes it easy for us wingers and people inside and outside him to play with because he's just so consistent.
"His communication is very good from a defensive point of view and he's probably one of the best passers of the ball in the squad.
"He has a bit of X-Factor about him when he gets the opportunity to put it on.
"He's been a key part of the squad and team over the last year or two."
Williams believes Ireland should promote Darren Cave to outside centre for Sunday's vital Pool D clash against Italy at London's Olympic Stadium.
Ireland will qualify for the quarter-finals with victory over the Azzurri and Williams is calling for changes.
"He's making really poor decisions: he's kicking the ball all the time and he's kicking very badly," said Williams of Payne.
"He's not making breaks. He's running across field.
"So, you can tick just about every box for doing things wrong as an outside centre in attack.
"I certainly do not believe that for us to go deep in the tournament that's going to be good enough.
"We have to get some centres that are going to show the ability to go through teams."
New Zealand-born Payne is likely to be reunited with usual centre partner Robbie Henshaw for Ireland's crucial Italy clash.
Henshaw is fit again after hamstring trouble, with head coach Joe Schmidt expected to restore his first-choice centre pairing.
Kiwi boss Schmidt has already accepted Henshaw and Payne form a "manufactured midfield" in his answer to the long-standing question of how to replace Gordon D'Arcy and Brian O'Driscoll.
Schmidt has found defensive ballast from shifting Henshaw from 13 to 12 and Payne from full-back to outside centre, and will in all probability continue to bank on the pairing.
"I think we're well used to it at this stage, that's why we don't watch it any more or read what they saying," said Bowe of Williams' criticisms.
"I know Matt Williams, I was coached by him.
"I don't think any of the players will be getting too upset about it.
"Maybe he's just playing the 'bad cop' role on TV, I don't know.
"I think, as a squad, the players would be very confident in Jared's ability.
"He's certainly one of the very popular lads around the squad, so I don't think he'll be getting too upset about it."