Martinez has introduced an attractive brand of football to Goodison Park since replacing David Moyes ahead of last season, yet that appears to have come at the cost of a solidity upon which the Scot's team was built.
Everton have already conceded as many goals as they did last term, 39, while a third of those have been the result of errors - by a long distance a Premier League high.
A 2-0 defeat at Arsenal on Sunday was sealed by Olivier Giroud catching the Everton defence cold from a corner before a Tomas Rosicky shot deflected beyond Howard's reach.
The American believes poor fortune has been behind a run of just one win from their last 11 Premier League games and remains full of faith they can arrest their slide down the table at the Britannia Stadium.
"That's the positive to take away from the last two or three months. We have got back to that hard-to-beat resiliency in the defence," Howard told his club's official website.
"It is disappointing when deflections happen, things that are very difficult to control. The back four have been playing well.
"We will go to Stoke City confident. When performances aren't right you start to wonder where the next one is coming from – that's not where we are.
"We feel confident individually and the confidence is rising within the team.
"Team performances have been good and if we do that against Stoke then we will get the result that we want."
Martinez's backline has been hit by injuries in recent weeks and Luke Garbutt is likely to continue at left-back in the continued absence of Leighton Baines (thigh) and Bryan Oviedo (hamstring).
Stoke come into the game with their own defence patched up, but the makeshift selection will be full of confidence after easily shutting down Hull City at the weekend.
Marc Wilson and Philipp Wollscheid will likely continue in the heart of defence, with Ryan Shawcross (back) and Marc Muniesa (hamstring) out.
Stephen Ireland is the latest Stoke player to be confined to the treatment room.
The Irish midfielder is likely to miss a number of weeks after picking up a badly cut calf during Saturday's 1-0 win over Hull in a challenge from Maynor Figueroa.
The last three meetings between the sides at the Britannia Stadium have ended in 1-1 draws – a late Baines penalty snatching a point for Everton last season.
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