It’s rare that a manager with such inexperience is considered for such high profile roles but the Hoffenheim boss has continued to catch the eye with the Bundesliga club since being appointed towards the end of the 2015/16 campaign.
He was thrust into the spotlight after Huub Stevens called a premature end to his time at Hoffenheim with the club in a relegation battle having won just two of their 20 matches.
Nagelsmann’s appointment belatedly kick-started the season for the club, with the new boss guiding his side to 23 points from a possible 42 on offer. This form saw them finish a point clear of a relegation play-off match and four points clear of automatic relegation
It was a baptism of fire but he passed.
However, for those familiar with “mini-Mourinho”, this wasn’t a surprise. Bayern Munich had already tried to bring him to the Allianz Arena after his impressive performances in charge of Hoffenheim under-19s.
The German giants wanted the Bavarian-born tactician at the club after he guided Hoffenheim to the Under-19 Bundesliga Championship during the 2013/14 season.
He turned down their advances and was rewarded by being named as the youngest Bundesliga manager in history at just 28 years old.
He grasped the opportunity with both hands. The 2016/17 campaign saw Hoffenheim go 17 games without defeat as the club stunned the German league to finish in fourth position, just two points behind Borussia Dortmund.
The achievement is more remarkable given the team lost another star name during the summer of 2016. Kevin Volland moved to Bayer Leverkusen and Hoffenheim, who failed to replace Roberto Firmino and Anthony Modeste in 2015, were even more reliant on their manager to develop any players they signed.
Hoffenheim signed loanee striker Andrej Kramaric to a permanent deal as well as bringing in Darmstadt forward Sandro Wagner. In midfield the club recruited Lukas Rupp from relegated Stuttgart, Kerem Demirbay from Hamburg and Kevin Vogt from Koln.
On paper, the quintet weren't world beaters but all played a vital role in Hoffenheim blitzing the Bundesliga with their fresh, unique approach.
Their squad wasn’t made up of stars but as a collective they could beat anybody on their day. And they did so time and time again.
Opting to go with a 3-5-2 shape, Nagelsmann worked with profiles as opposed to traditional positions. He utilised Vogt, a midfielder by trade, as a ball-playing centre-back. Demirbay and Tottenham Hotspur transfer target Nadiem Amiri both started life as attacking midfielders but the Hoffenheim boss convinced them that they'd excel as box-to-box midfielders in his system. They were.
Aided by the use of drones to film his squad's movement, Nagelsmann also had a giant videowall installed on the halfway line of their main training pitch so he could give instant feedback to the players on how they could improve.
Wagner was the focal point of the team. His aerial presence was used to bring others into play, and it was hard to stop. Nagelsmann used a high press in an attempt to overload central areas. The closer his team were to Wagner, the more chance they had of creating chances. The counter-pressing style married well with that tactic.
However, Nagelsmann and his team struggled to replicate their 2016/17 form at the start of the 2017/18 campaign. The departures of Niklas Süle and Sebastian Rudy to Bayern Munich hurt with the replacements not being the requisite quality needed. The club aren’t in a position to replace like for like and have to settle on slight downgrades which in turn makes the starting XI weaker.
The uncertainty surrounding the manager's future also had an impact on the team, as did having to play in European competition. They went four games without a win on two occasions in the first half of the season.
Bayern then came calling for a third time and poached Wagner in January. In the space of six months Hoffenheim had lost four of last season's starters with Demirbay ruled out with an ankle injury.
Nagelsmann was under pressure. Many believed his first full season in charge was the perfect storm and that this campaign was the young manager's real level.
But he dug deep, regrouped and came up with a new system to get the best out of his squad. Since the start of February, Die Kraichgauer have lost just one match in all competitions. They've won seven of their 12 games, scoring 31 goals in the process.
The new look forward line is thriving and it's all down to the tactical tweak implemented because Wagner left the club.
Serge Gnabry, Mark Uth, Ádám Szalai and Kramaric are all much quicker than the former Hoffenheim forward so the team are now much faster when attacking. It's shown in the team persona model above.
Prior to Wagner's departure, the build-up play was much slower so that players could get up in support of the 30-year-old target man.
Now, Nagelsmann's men are ready to counter teams with pace to burn in their forward line. The likes of Gnabry and Kramaric are transition players, they come alive when the opposition are looking to move from a defensive position into a more attacking one. Their pace scares defences and this creates opportunities for them, ones they wouldn't have carved out with Wagner leading the line.
Yes, the team would press but to have three players in attacking positions who gobble up the ground brings a different dynamic to the side.
The screenshot above, taken during Hoffenheim's 5-2 win over RB Leipzig, shows how the forward line presses. The home side try to play out from the back the passing lanes are blocked.
The ball is played to the left centre-back who takes a touch and attempts to go back to the keeper, but the speed in which the forward line close down the space means they're able to steal the ball and all three are clean through on goal. Gnabry calmly strokes home his first and the team's second of the day.
Nagelsmann has shown he can cope with losing star players. He's showcased that he's a flexible manager as well as a master tactician, the subtle tweaks he's made to the 3-5-2 shape have got his team into the race for Champions League football, again. He's getting the most out a team who are clearly punching above their weight and have been for two seasons now.
He's the perfect modern-day manager and if a club wants to build a legacy then he's the manager for it. With many clubs in the Premier League heading into a transitional period, it might not be too much of a gamble to appoint the 30-year-old.