The Mexican sharp-shooter netted 28 league goals in a prolific two-year stint at the BayArena, but opted to join English Premier League outfit West Ham United on the back of the North Rhine-Westphalian outfit's underwhelming twelfth-placed finish in 2016/17.
With 'Chicharito' gone, who was going to score the goals to lift Bayer away from the relegation zone and back into the frame for a UEFA Champions League berth? The answer to that question has been answered emphatically in recent months.
Watch: Leverkusen's tactical masterclass
In the absence of Mexico's all-time top scorer, three players in particular have stepped up to shoulder the goalscoring burden at Leverkusen. Leon Bailey, Lucas Alario and Kevin Volland have netted over half of Bayer's 41 league goals so far this term, catapulting Heiko Herrlich's side to the dizzying heights of second in the table after Matchday 20.
With eight strikes and five assists to his name in 2017/18, Jamaican winger Bailey has been directly involved in more goals this season than any other Leverkusen player. Blessed with extraordinarily quick feet, a powerful shot and blistering pace, Bailey has more strings to his bow than Hernandez, who was known predominantly for his predatory instincts inside the opposition penalty area during his time at at the BayArena.
Watch: Leon Bailey: a defender's worst nightmare
Indeed, Bailey's dribbling skills and long-range shooting ability have drawn favourable comparisons with none other than Bayern Munich's Arjen Robben. The Bavarians' flying Dutchman would have been particularly proud of Bailey's goal in Bayer's recent 2-0 triumph over Mainz - a 25-yard piledriver into the far corner of the net after the 20-year-old had cut in from the right wing onto his left foot - not to mention his majestic backheel against Hoffenheim a week earlier.
While Bailey is unlikely to lose his place in Herrlich's starting XI anytime soon, the former Genk star has also demonstrated a useful knack of scoring important goals from the substitutes' bench. The 20-year-old netted Leverkusen's equaliser in a 1-1 draw at Schalke on Matchday 7 and scored twice in a pulsating 4-4 draw at Hannover on Matchday 17, having entered the fray at half-time in both matches. Hernandez, by contrast, failed to score in any of the six games in which he was brought on as a substitute.
Alario, meanwhile, has wasted little time in firing his way into Leverkusen fans' hearts since his summer move from River Plate. Affectionately known as 'El Pipa' (the rifle) in his native Argentina, the 25-year-old has registered five goals in twelve league appearances for Die Werkself to date, including one on his Bundesliga debut - something Hernandez failed to achieve on his Bayer bow in September 2015.
His two assists in the victory over Mainz lifted the Albiceleste international onto three for the season - Chicharito's assist total in both the 2015/16 and 2016/17 campaigns. He remains some way off Hernandez's overall Bundesliga goals tally of 28, of course, but if Alario can maintain his current strike rate of a goal every 125 minutes (Hernandez only averaged a goal every 130 minutes), it won't be long before the former Colon forward draws level with the Mexican in the club's all-time scoring chart, too.
Watch: Relive Alario’s debut goal for Leverkusen on Matchday 6
As for Volland, he has already improved on his six-goal haul from last term, when injury restricted him to just 16 Bundesliga starts. With ten goals to his name so far this term, the Germany international forward is just eight goals shy of eclipsing Hernandez's 2016/17 haul of 17 league strikes. The former 1860 Munich and Hoffenheim attacker is on course to equal that tally at the very least, having averaged over a goal every other game so far this campaign.
While Hernandez was only ever deployed as a central striker during his time at Leverkusen, Volland is more than capable of operating in a number of positions across the front line. So far this campaign, Herrlich has used the Germany international in the the hole behind the main striker, on both the left and right wings and even in attacking midfield.
Volland's versatility does not dilute his overall goalscoring impact, though: Despite starting on the right flank in the 5-1 victory at Borussia Mönchengladbach on Matchday 9 and on the left in the 1-0 triumph at Eintracht Frankfurt on Matchday 13, the 25-year-old managed to get his name on the scoresheet in both games, further underlining his emergence from Chicharito's shadow.
Watch: Check out Volland's winner against Eintracht Frankfurt on Matchday 13
There is no denying that Hernandez left an indelible mark on the Bundesliga during his 24-month spell in north-west Germany. However, with Leverkusen's current attacking triumvirate of Bailey, Alario and Volland plotting Bayer's path back into the Champions League at the first time of asking, the Little Pea's departure is not being felt as keenly as the BayArena faithful had originally feared.