Many have seen this as a statement of intent by Roberto Martinez's side, who for the past few years have become more accustomed to receiving large payouts rather than making them.
However, what’s received less coverage is just what a massive risk this is for Chelsea. Even with the signing of Diego Costa for around £32 million from Atletico Madrid, their attacking situation is far from perfect, and they could well find themselves ruing the decision to let Lukaku leave.
Lukaku’s strengths as a player are obvious. His power and ability to hold the ball up made him a natural successor to Didier Drogba in the Chelsea setup, and he was a relatively rare commodity given his proven goalscoring record in the Premier League.
In an ironic twist, it appears that Drogba’s return to the club was the deciding factor in Chelsea selling Lukaku.
While it may well prove to be the case that Costa can carry on his stellar form from last season, he’s still a bigger risk than keeping Lukaku would have been. While he was excellent for La Liga winners Atletico last term, he no doubt benefited from being the main striker at a top club in a high-scoring league. Atletico’s superb attacking support, led by Koke, was also a major factor.
His 27 league goals in 35 appearances last season was a fantastic return. However, the rest of his career has been largely average, and at age 25 there are doubts as to whether Costa's form last year was a sign of things to come or a flash in the pan. Chelsea have been stung in the past when signing strikers without experience in the league, such as Andriy Shevchenko and Mateja Kezman.
Alongside Costa, Chelsea have extremely limited options. Samuel Eto’o, who performed admirably as a stopgap in the twilight of his career last season, has left the club. Drogba may have returned, but it’s hard to imagine him being anywhere near as effective as he used to be. And Fernando Torres has shown no signs of turning his disastrous form around.
Lukaku is still only 21 and has scored a respective 17 and 15 goals in the last two seasons. Both tallies are made more impressive when considering the fact that neither team he was playing for was competing for the league as Atletico were last term.
It’s hard to imagine that he won’t continue to improve. By age 25, there’s a strong chance he will have surpassed anything Costa has achieved thus far.
Chelsea may have had one eye on Financial Fair Play regulations with the decisions to buy Costa and to sell Lukaku, as they have almost balanced the books in that respect. However, Lukaku counted toward the club's homegrown quota, and with Ashley Cole and Frank Lampard also leaving the club, Chelsea could now have issues naming a full squad in the league and Champions League.
Time will tell whether Costa is able to hit the ground running and if Jose Mourinho’s decision is vindicated, but it’s hard to understand why Chelsea are facing this anxious wait in the first place.
Costa may be able to offer slightly more in terms of goalscoring for the time being. But as well as being younger and counting as homegrown, Lukaku represented all benefits and no risk.