Two games into the Premier League season, it all seemed pretty simple. Once Thomas Tuchel took the Chelsea job in January, they became the best defensive team in the world. Over his 19 Premier League games in charge, they allowed 13 goals -- a 43% decrease on the 23 goals allowed in the season's first 19 games under Frank Lampard.
Under Tuchel, they conceded 7.9 shots per game -- fewer than all but two teams in Europe's Big Five leagues allowed last season. And the average expected-goal value of each shot they allowed was just 0.08 -- meaning the average shot Chelsea conceded had an 8% chance of turning into a goal, compared to the Europe-wide average of about 12%. Only one team limited their opponents to worse attempts, and all in all it added up to 0.6 expected goals allowed per game, which, over the course of a full season, would've been the lowest rate in Europe.
That impenetrable defense propelled Chelsea back up the Premier League table into the Champions League places come season's end. Oh, and they won the Champions League, too. In the final, they held Pep Guardiola's Manchester City to just seven shots and a meager 0.45 xG -- City's third- and second-lowest totals in those respective metrics since the Spaniard arrived in 2016.
Teams weren't supposed to win titles like this anymore -- and they rarely did. The previous six Champions League winners averaged 103 goals scored in domestic play. The peaks were Barcelona in 14-15 and Real Madrid the following year, both with 110, while the trough was the 17-18 iteration of Madrid that finished with a pathetic 94.
Chelsea wrapped up last season with ... 58 goals in domestic play, and their scoring rate actually dropped off once Tuchel took over, as they scored 25 goals in his 19 Premier League matches, which would add up to 50 goals for a full season. Ten teams in the Premier League scored more than 50 goals last year. With their sights now set on a Premier League title, that just wasn't gonna be enough. An elite defense could carry you across the seven-game volatility of the Champions League knockout rounds, but you simply just couldn't win enough matches over a 38-game season unless you started significantly outscoring the likes of Leeds United and Aston Villa.
One easy way to fix that? Sign the best striker on the market and plop him on top of that impossible-to-score-against defense. But has it really worked out?