In the Premier League this term, Chelsea boast one of the strongest defences in the division and their impressive statistics back this up.
According to Understat, only Manchester City, Newcastle United and Arsenal have conceded more expected goals than the Blues tally of 13.43.
When you marry that figure with the 12 goals Mauricio Pochettino's side have conceded this season, it is crystal clear that their defensive solidity is down to the manager's tactical nouse as opposed to impressive recruitment.
In the transfer window just gone, Chelsea focused on bolstering the goalkeeper department after seeing Edouard Mendy depart permanently and Kepa Arrizabalaga leave on loan, with the Argentine bringing in Serbian, Djordje Petrovic and Brighton & Hove Albion's Robert Sanchez.
While the latter of the two has established himself as the club's number one, he hasn't filled many of those with confidence in between the sticks, especially after the blunders he dropped in the 2-2 draw against Arsenal.
With that said, supporters will be pulling their hair out knowing they could have had a quality goalkeeper commanding their backline instead – and that player surprisingly isn't Thibaut Courtois.
How much Chelsea sold Marcin Bulka for
In the summer of 2016, Chelsea acquired 16-year-old goalkeeper Marcin Bulka from FCB Escola Varsovia, just months after he went on trial with Barcelona.
The youngster featured sparingly across the various underage groups at the club in the years that followed, making just 31 appearances across three seasons.
Despite making a solid five clean sheets in 19 matches for Chelsea's under-21s, he was never given an opportunity to impress in the first-team and subsequently departed the club on a free transfer in 2019, with Paris Saint-Germain snapping up the Polish shot-stopper.
While they wouldn't have known it at the time, the club have been made to regret letting him go for nothing as he's since established himself as one of the most promising young goalkeepers on the planet with OGC Nice.
Marcin Bulka's statistics at Nice
Prior to this campaign, the 24-year-old had only racked up 27 appearances at senior level across spells at PSG, FC Cartegena, LB Chateauroux and now Nice.
Bulka had become accustomed to playing understudy in the early stages of his career and last term, was forced to watch on for most of the season at Nice as Kasper Schmeichel played a starring role in between the sticks, making 11 clean sheets across 35 appearances in Ligue 1 before departing the club for Belgian Pro League side Anderlecht this summer.
The Dane's departure signalled the chance for the former Blues man to grab the number one jersey and he's done so in style. Not only has he kept eight clean sheets and conceded just four times in 11 appearances, but those vital contributions have helped his side gain the edge over his former employers, PSG, at the top of Ligue 1.
Hailed as "absolutely sensational" for his incredible form in France by talent scout Jacek Kulig, Bulka is the latest initiation to the list of players that Chelsea have cursed letting go, particularly in the goalkeeper department, having replaced the world-class Courtois with Arrizabalaga in 2018.
When delving deeper into the statistics and comparing his form this season to Sanchez, it is clear that the 6 foot 6 goliath would have been a huge upgrade on the Blues' current shot-stopper.
Statistic
Robert Sanchez (Premier League)
Marcin Bulka (Ligue 1)
Goals conceded
12
4
Saves made
29
23
Goals prevented
-0.82
3.81
Clean sheets
3
8
Penalties saved
0/1 (0%)
2/2 (100%)
Accurate passes per game
25 (82%)
26.9 (88%)
All stats via Sofascore
As delineated by the above statistics, although Sanchez has made more saves – perhaps because Chelsea are put under sustained pressure – Bulka comes out on top in every other department, with the most telling metric of the lot being how many goals he's prevented, 3.81 to the Spaniard's -0.82.
Aside from smashing Sanchez at the goalkeeping fundaments, impressing with his reflexes and command of area, the Polish international is also better with the ball at his feet, accurately placing more passes than his compatriot.
At the age of 24, Chelsea would have saved themselves millions in the transfer window if they had kept Bulka, who looks seemingly destined to become world-class.