Head coach Jindiich Trpisovsky, who took over the team in December 2018 and has been in charge for all eight seasons, is the main reason for Slavia's total dominance in this respect. Moreover, the club have not only been the top defensive team in the Czech league during this period, but also one of the very best across the top 10 European leagues.
Trpisovsky's emphasis on defence is obvious. In those eight seasons, his side had the most productive attack after the regular season on five occasions, but their focus has always been on the backline, even when they have not been the best in the league.
This is nicely illustrated by the season just before Trpisovsky's arrival, in which Slavia won the title under Jaroslav Silhavy, scoring considerably more goals than second-placed Plzen.
But for Trpisovsky, working from the back was still simply a priority. "We want to lean on our defensive line, it's a long-term trend," he said last August.
The result? Only 11 goals conceded in 30 rounds this season, in 20 of which Slavia have kept a clean sheet. There were only better in the 2019/20 season (10 goals conceded with 22 shut-outs).
These are extraordinary numbers, and not only in the context of the Czech league, as even the coach of the Red and Whites himself has noticed it.
"We have the fewest goals conceded in the league and the most clean sheets in Europe. When I look at the big teams in the top competitions, not many play so many dominant games," he said after the last game against Slovacko, in which his team (as usual) did not concede. Although he was talking only about the current season, his words are valid for the last eight seasons.
In that time, Slavia conceded 170 goals in 269 league games (an average of 0.63 per game), which is the best in comparison not only within the top 10 European leagues (according to the current UEFA coefficient rankings), but also with comparable competitions from neighbouring countries (Austria and Poland).
Only clubs with at least 200 games played were taken into account for this. Second in this ranking is FC Porto (268 matches/187 goals against/average 0.70), third is Benfica (268/209/0.77).
Slavia also clearly rule Europe in the number of clean sheets, having collected 144 in eight years. Only Porto (135) have managed to do so in the vast majority of their games (54%), followed by giants Manchester City (131), Barcelona and Atletico Madrid (129).
Now the question before them is not whether they will win the title, but rather when. As the Czech champions, they are guaranteed a place in the main stage of the Champions League next year and will go there as Europe's current kings of defending.
Their 20 clean sheets this season are matched by nine clubs with 15 (including Juventus, Napoli, Porto), while their closest competitor with 11 goals conceded is Poland's Czestochowa (19, with one game fewer).
Advanced data shows that Slavia does not even let the opponent into dangerous situations. Of the 213 clubs monitored, they have faced the second-fewest number of attempts on goal (212) and accurate shots on target (69). Only Bayern Munich are better in both metrics (192, 66).
In total, four of their 11 goals against were scored from headers, which is an average number in Europe (for example, Napoli got none). However, that doesn't quite mean that the Czechs have a weakness in the air.
After all, the Czech league is characterised by a huge volume of crosses, and among the 10 clubs with the highest number of aerial duels taken, five are from the Czech top flight.
Slavia are ranked 27th in Europe (and 10th in the Czech League) with 1,150 such duels. However, they still have an excellent 57.2% success rate with 658 header duels won and are third on the continent behind only Inter Milan (58.8%) and Rapid Vienna (57.7%).
They are then second in the number of presses. In total, they have 503, only Cercle Brugge (636 in four games more) are better in this respect.
For example, fourth-place Barcelona (477) are behind Slavia. The Prague side are also one of the top teams in terms of the percentage of successful attempts to turn the ball over from the opponent.
At 64.1%, it is the 16th highest in Europe, and interestingly, it is only slightly above average in the Czech Republic. They are only fifth in the league, with Banik Ostrava having the highest success rate (and across all leagues) with 68.6%.
Next season, it will be very interesting to see how the continent's best defence will fare in tougher competitions against the best attacks.