It has been difficult for the Rovers head coach, who has only just gained the luxury of having four centre-backs available following Scott Wharton's return.

For most of the season, it has been flip-flopping between Hayden Carter, Tom Atcheson and Sean McLoughlin, either rotating a pair or using all three, on occasions.

But that chopping and changing - admittedly somewhat enforced by Carter's injury record - may not be helping them.

In each of the last six games, Rovers have changed their centre-back set-up. Whether that's the personnel or adding/removing a defender. West Ham is likely to be the first time since mid-September that they've named the same set-up in consecutive games.

It was the goals for column that badly let Rovers down last season. They were second-lowest scorers in the division behind the destetute Sheffield Wednesday but only four teams, all in the top five, conceded fewer than their 56.

This season, that has completely switched. They have almost averaged 1.5 goals per game in attack but only nine teams have conceded more.

Whilst there will always be an element of rotation with Carter and Wharton in the squad, Mowbray needs to find some consistency in selection to help Rovers' goals-against column.

"You like to have consistency for centre halves, and yet when I came in, however many months ago, Hayden was injured and Scotty was injured," Mowbray explained.

"They were two really experienced footballers at this level and gradually, they're both available at the moment, which is good.

"Yet we've got young Tom who's going through the development of being a really good footballer somewhere down the line, learning his trade as he goes, I think.

"Sean at the other end of that, who's around 30. He's an experienced vocal centre half that can bring some steadiness to the team.

"My decision is whoever we play to try and get the right balance without chopping and changing every single week and not giving them time to gel together and understand their weaknesses and the strengths of each other."

Blackburn Rovers' Hayden Carter. (Image: CameraSport - Dave Howarth)

There has been perhaps too much deviation in system, at times. Mowbray likes to play with a back four, certainly at home.

That obviously asks more physically of his defenders, making Carter's athleticism more important.

Atcheson, by contrast, has probably looked at his best in a four, for club and country. It was on the right of the back line where he broke through for Michael O'Neill and has established in that role for his country too.

It is clearly against Mowbray's nature to prefer that shape despite the record of recent Rovers bosses landing on it as the best way forward.

I personally prefer Rovers in the 4-2-3-1 shape but clearly, they need to pick something and stick with it.

"If anything, it's a decent dilemma for me that I've got four when they're all available to pick from," he continued.

"I have to make the call on who I think in which game is going to get the job done. Occasionally we play three at the back if we feel it's the right thing to do on any given day. But I don't just want to pick the system to get players in.

"I want the team to feel a function. I feel, particularly at home, playing a four, playing two centre-backs, gives us more attacking players on the pitch and allows us to play through the lines of the opposition better with more options to play.

"Potentially away from home, I might look at me and make his more solid and not worry about how much of the ball we have and stuff like that.

"We have to find a way, which is what I'm trying to do - find a way to be consistent home and away. But the games are obviously different."

Wharton has not played consistent minutes for 12 months, having gone off with an Achilles injury midway through last November. He's managed just two notable appearances since.

Yet he has now been fit for more than a month, using Under-21 games to find match sharpness. Without playing Championship football, Rovers won't know if he's ready or not, at this stage.

"He's played a couple now (U21 games); he played last week," Mowbray said.

"He's a very good professional, Scotty Wharton, and he generally asks me if it's okay can he play this game on Friday night or Monday? Because he hadn't been involved at the weekend or he's not going to be involved at the weekend. He'll want to play 21s, which is a real positive.

"I think he has to build up his robustness and so that he can trust his body somewhere down the line when needed to play two games a week or three games a week, even.

"I think that's been an issue with him because of the injuries one after another over the recent periods."