The 53-year-old Dane had been out of work since resigning from the national team job back in July 2024, and whilst his hire isn't necessarily a left field appointment, given that his only previous experience in one of the top five European leagues came way back in 2014/15 with Mainz, it could be said to represent something of a gamble at this particular moment.
Ten Hag, unfortunately, was possibly the right man but at the wrong time, because whoever it was that took over from Xabi Alonso, they were on a hiding to nothing.
How could they not be after a season that saw them come within one game of an unbeaten treble - a feat that would've unlikely have ever been repeated - and then a decent enough follow-up campaign.
To the Spaniard's credit, staying on for a further season was laudable, though no one was ever in any doubt that he would soon move on.
Erik ten Hag was on a hiding to nothing at Leverkusen
The problem for Ten Hag is that so did many of the players who bought into Alonso's vision.
Arguably the team's most creative player, Florian Wirtz, moved to his former manager's former club, Liverpool, and was joined by Jeremie Frimpong.
Amine Adli, Odilon Kossounou, Victor Boniface, Gustavo Puerta, Lukas Hradecky and Jonathan Tah were others to leave, with Granit Xhaka and Piero Hincapie moving on after the Dutchman had put pen to paper to take over in the dugout.
It was undoubtedly the sale of Xhaka which showed the football world how little influence ten Hag had at the club despite only just stepping into Alonso's shoes.
When rumours were swirling that the former Arsenal man might join Premier League newcomers Sunderland, the Dutchman was unequivocal in his opinion, telling reporters, "Granit is a leader, he has signed for five years and has three years left on his contract. He's too important for us to let him go."
Within a few days the player had been sold.
Just 62 days in charge
It was around that time that Leverkusen had lost 5-1 to Flamengo's U21s side during what was supposed to be a warm-weather training camp, and if anything, that was a precursor for things to come.
Beating SG 4-0 in the German Cup was Ten Hag's only non-friendly win during his 62 days in charge.
A week later Leverkusen lost at home to Hoffenheim, before leading 3-1 at Werder Bremen, only to then draw 3-3 despite the opposition being down to 10 men.
Coupled with an attitude which apparently was alienating many members of the first-team squad, the club acted quickly whilst admitting they'd made a big mistake in the process.
Hjulmand's record doesn't make for great reading
With Hjulmand now at the helm, the hope would be that the ship will be steadied, but the Dane's record doesn't necessarily make for great reading.
For example, since 2014/15, when in charge of Mainz, Hjulmand has overseen 165 games. Only 66 of those have been wins, with 54 losses.
His win percentage in his previous Bundesliga stint was an appalling 20.8%, and he was sacked in the February of 2015 by Mainz after a run of one win in 13 matches.
His best club win percentage (17 wins from their 36 games played which translates to 47.2%) came as far back as 2017/18 with FC Nordsjelland, and though his teams in the past 10 years (including the Danish national team) have scored some 287 goals, they have conceded 243.
They are hardly figures to get excited about, and the issue for Leverkusen sporting director, Simon Rolfes, is that Alonso's unbelievable success at the club now has to be seen in context.
It simply isn't going to be possible for a new manager to come in and replicate that one-off campaign, particularly with a number of players who got them there no longer at the club.
Knee-jerk reaction from Leverkusen?
One could even suggest that the reaction to Ten Hag's first nine weeks was a little knee-jerk, so how the board and directors react now is almost as important as what happens on the pitch.
For any new manager to be able to build properly, they need to be given time and a few transfer windows in order that they are not encumbered by what has gone before.
Hjulmand comes into a team that are down in 12th place in the Bundesliga table and with a negative goal difference, but with only two games played of the 2025/26 German top-flight season.
Their next assignment is a fixture against joint table-toppers Eintracht Frankfurt, followed by a Champions League trip to Copenhagen.
By the time the club host Newcastle in the premier European tournament on December 10, Hjulmand will have been in charge for 18 games and Rolfes and his other directors should have an inkling by then of whether they have the right man for the job or if they've made another poor decision.
