Sam Allardyce is a manager who is famed for his ability to transform leaky outfits into sturdy, unbreakable defensive units, but he did little to justify that reputation during his time at Goodison Park.

With a hapless defensive combination of Ashley Williams and Michael Keane marshalling the back-four, Everton supporters winced with fear on a consistent basis last season as the opposition began to orchestrate their next attack. Playing with about as much conviction as a groggy-eyed Sunday league defender trying to gather some basic coordination after a prolonged evening down the local, Williams was a complete liability at the heart of defence last season.

Keane wasn't much better, but he didn't stand too much of a chance alongside a player who was clearly well out of his depth at this level. But with a £25.65 million price-tag on his head and a glowing reputation from his two-year spell with Burnley, the Toffees faithful were well within their rights to expect much better from the 2017 recruit.

Enter Marco Silva, a new philosophy and a new partner in Kurt Zouma, and Keane is finally beginning to justify Everton's decision to part with a hefty fee for his services. Barring a ghastly skull injury which fortunately ruled him out of just two fixtures earlier this season, Keane has been a mainstay at the heart of the back-four and he thoroughly merits his importance to the squad.

Not only does Keane look markedly more assured and reliable in the back-four, he is beginning to hone in on his technical quality under a manager who sits at the opposite end of the philosophical spectrum which Allardyce occupies.

According to Evertonfc.com, 'Keane is averaging 49 passes per match this term – nine more than he was making on average in games last season,' while his pass completion rate has increased from 78% to 82% so far this season.'

But Keane's contribution moving forward does not start and end with his ball retention, as his commanding aerial presence could prove to be a valuable weapon this season, according to the former Everton attacker Graham Stuart (via Evertonfc.com).

“Everton have some very powerful players in the air and Michael is one of them.

“If we have good delivery from wide areas, especially from set-pieces, we carry a real attacking threat in those situations."

Standing at 6'2", Keane possesses the height to make himself a nuisance in the opponents penalty area. The England international showcased that ability earlier this season as he towered above the Bournemouth defenders to squeeze a strong header underneath Asmir Begovic following a deliciously appetising ball from Gylfi Sigurdsson.

That his strike at the Vitality Stadium was just his second goal in an Everton shirt suggests that he needs to work on his positioning in the penalty area, and also communicate with his creative teammates to ensure he penetrates the right areas from set-pieces.

First and foremost the effect Silva has had on Keane's defensive contribution has been the most integral improvement in his game this season, but it's also refreshing to see that he is adapting to the possession-based philosophy and demonstrating an improvement in his ball retention.

If Keane can continue to rise up the exponential curve he currently finds himself on and utilise his physical presence to notch a few goals over the course of the season, there's no doubt he will re-write the wrongs of his maiden campaign on Merseyside - a notion that Silva deserves huge credit for.

Everton fans - thoughts on Keane? Let us know below!