The Argentinian stopper arrived at the Etihad Stadium in a £28.5million deal from Valencia in the summer of 2015, and his first two seasons in England were marked out by occasional costly errors of judgment and an inability to shore up the Manchester side's backline as desired.
But 2017/18 has been a much more pleasing term for the bearded Buenos Aires-born defender, on both an individual and team basis.
With club captain Vincent Kompany continuing to battle injuries, Otamendi has become the constant of the City defence, the man Pep Guardiola relies upon for solidity and technical quality.
And despite City's processional march to the Premier League crown, amassing 100 points and setting new high-marks for goals scored, goal difference and wins, their defence has not been as settled as Guardiola would have hoped.
In addition to Kompany's fitness problems, John Stones suffered a post-New Year crisis of confidence, mid-season record signing Aymeric Laporte has been eased into his new surroundings, and an injury to left-back Benjamin Mendy early in the season meant midfielders Fabian Delph and Oleksandr Zinchenko have had to adapt to unfamiliar defensive roles.
There throughout, however, dependable to the end and newly consistent in all his duties, was Otamendi.
There role of a centre-back at City is unlike most other clubs. Guardiola's men enjoyed a whopping 66.4 per cent possession on average in the Premier League this season, meaning their defenders are in action on the ball more than others, and are tasked with winning the ball back less often.
As such, passing ability becomes arguably the key attribute for a City defender, and Otamendi, as the above Football Whispers Player Persona diagram shows, has been incredibly effective in this department.
Indeed, no player in the Premier League made more accurate passes than Otamendi this season, while the former Porto centre-back also ranked in the top ten for total forward passes.
Although Otamnedi performed magnificently on 2017/18, he was run extremely close in the voting for the Football Whispers Central Defender of the Year by Tottenham Hotspur‘s Jan Vertonghen.
The Belgian also enjoyed a stellar campaign, offering consistency and leadership and Spurs dealt with injury and form issues afflicting Toby Alderweireld and Danny Rose, while bedding in the raw talent of Davinson Sánchez.
As the above graphic shows, statistically there was little to separate Otamendi and Vertonghen, with the latter edging the defensive numbers, while the former performed slightly higher with the ball.
Ultimately, though, having been key to one of the most successful domestic seasons in the history of English football, Otamendi gets the nod, and few would argue the Argentinian has produced a campaign worthy of such recognition.
With the World Cup approaching and Argentina, led by the one and only Lionel Messi, will hopeful of claiming football's grandest international honour for the first time in 32 years.
Where once they possessed wonderful attaching talent but were hamstrung by defensive frailty, Otamendi's form and confidence could see Jorge Sampaoli's men go one step further than the runners-up spot they attained four years ago in Brazil.
And when he returns to club duty for the 2018/19 Premier League campaign, win or lose at the World Cup, his place in the City side will be assured. Previously considered a weak link, Otamendi's is now Guardiola's Mr Reliable.