It was the Spaniard, who was followed by Quique Sánchez Flores and interim head coach Hayden Mullins, who kickstarted the Frenchman's renaissance at Vicarage Road.
Pearson has continued it, and how.
Plenty of players have felt the benefit of working under the former Leicester City manager. Kiko Femenía and Adam Masina have established themselves as Pearson's first-choice full-back pairing having previously served as deputies to Daryl Janmaat and José Holebas.
In midfield, Abdoulaye Doucouré has been pushed forward to great effect while Will Hughes is enjoying his best run of starts and displays in some time. Both men owe a debt of gratitude to their midfield partner-in-crime: Capoue.
It hasn't always been this way. The 31-year-old was a bone of contention in his first couple of seasons in Hertfordshire. Briefly Watford's record signing at £5.7million following promotion in 2015, the former France international was lackadaisical, only affecting games in fleeting moments or – so it seemed – in big, often televised, matches.
But no more.
The appointment of Gracia in January 2018 proved a masterstroke for Watford for so many reasons. And while the likeable Spaniard was unceremoniously turfed out after just four games of the current campaign, guiding the Hornets to only their second-ever FA Cup final and highest Premier League finish will not be forgotten.
Nor will his impact on Capoue. It had never quite been clear what the rangy midfielder's best role was following his switch from Tottenham Hotspur. There was an expectation that a player with his physical and technical gifts would be a midfield driving force and creator. Yet it took until his second season in WD18 to even register a goal.
A run of four in the first six games of the 2016/17 season was a red herring, though. Capoue's best performances have always come when stationed at the base of midfield, patrolling the middle third, snapping into challenges, snuffing out dangerous opposition attacks and starting Watford moves with his impressive range of passing. There probably isn't a better passer to have graced Vicarage Road in his five years.
There are times when the former Toulouse prospect straddles the line between tenacity and idiocy, though. Capoue has a misguided penchant for throwing himself into challenges with the kind of force that makes supporters anxious.
Again, this wasn't always the case. There was a time when he gave off the impression he was working really hard, pumping his arms in a unique running style which made it look like he was busting a gut to get to the scene of the crime, only to just let the perp escape.
Now he is Watford's action man, at the epicentre of everything. And the stats reflect it.
Since January 11, the amount of defensive work Capoue gets through has increased dramatically. Comparing the period from November 7 until January 11 against the latter date until the present, there has been a stark contrast in his output.
Since the turn of the year, the Niort native has attempted more tackles (per 90), rising from 2.23 to four. That sort of increase doesn't automatically necessitate a rise in the number of completed tackles. But Capoue is winning the ball back with greater frequency than before.
Capoue has also seen the number of interceptions he completes almost double while he is winning more duels (9.13) than before (5.58). What makes this transformation even more impressive is the fact his position on the field has hardly changed. He is now one of two deeper-lying central midfielders, rather than the three favoured by Sánchez Flores.
In order to get a better idea of what has changed, we've looked at Capoue's defensive actions maps for the two time periods, showing all tackles, interceptions, blocked passes and fouls. What immediately becomes evident is the Hornets' No.29 is now trying to cover a smaller area of the field, making him more effective.
The reintegration of the aforementioned Hughes has been a big factor in this. The former Derby County prodigy has taken up a similar role alongside Capoue, screening the back four while freeing up Doucouré to use his long limbs to power forward as No.10.
And Capoue is in no doubt as to who is responsible for his own performance levels, as well as those of the team, improving in the last few months.
“Every manager has their own ideas, but I think Nigel has brought the feelings that you can do more than you think,” Capoue told Watford's website.
“We do a lot on the pitch and we fight for each other, and that’s what he’s brought. You can see the atmosphere between the players is unbelievable, even since the beginning of the season, but now we have good results everyone can see it.”