It’s true the Dudley-born chief does tend to polarise opinion.
It’s also true the Baggies have been relegated under his watch.
But even though they have gone down, the team has made huge strides forward in his five months at the club.
Don’t take my word for it, the players say it themselves.
“We’ve played a lot better under Sam, have looked more organised as a team and have been better going forward,” Conor Townsend said this week.
Fellow defenders Kyle Bartley and Dara O’Shea have also said similar things on record.
Yes, the 66-year-old didn’t get the results everyone hoped for. But he did transform a struggling side into one that was competitive in the Premier League every single week.
“We got very close (to survival) even if the points tally doesn’t show it,” he said shortly after confirming he is to leave the club. “We got so so close to winning enough games to stay up but we didn’t quite make it.”
Allardyce improved Albion for the simple reason he is a talented and vastly experienced boss who knows what he is doing.
He immediately noticed the players he inherited weren’t fit enough.
He also noticed the squad was desperately lacking a conventional holding midfielder and striker.
And while his first 10 games were a disaster, the team quickly improved when he got his additions and the players in better shape.
Allardyce knows what he is doing – particularly when it comes to organising a defence. And that is something Albion have lacked in recent years.
As good as they were under Slaven Bilic at times last season, the Baggies struggled to keep to clean sheets.
It was the same story under Darren Moore.
But under Allardyce you know they would have gone into the Championship with solid foundations.
And with additions to go alongside Grady Diangana, Karlan Grant, Matt Phillips, Robert Snodgrass and Callum Robinson – they would also have been dangerous going forward.
There isn’t a manager in the world who can guarantee he can get Albion back into the Premier League at the first time of asking. But it’s hard to imagine the Baggies finishing lower than sixth under Big Sam.
And that is why the club wanted to keep him and why losing him is a blow.
There is one positive to his departure though.
Along with Diangana and Grant, the likes of Jake Livermore and Romaine Sawyers have also been cast aside by Allardyce this season.
Having cost the best part of £30million, Diangana and Grant simply have to be reintegrated into the team.
Livermore and Sawyers may have to be as well.
You get the feeling that will be easier to do with a new boss at the helm – a new manager gives those players a fresh start.
Whoever that man is, they’ve got a huge rebuilding job to do with it likely the Baggies will lose Matheus Pereira and Sam Johnstone this summer.
You’d trust Allardyce to get that rebuild right. He is going though. And that means the pressure is on to find another manager who can also secure a quick return to the Premier League.