Alban Lafont has been a source of fascination since the moment he became Toulouse’s starting goalkeeper at the age of 16 during the 2015–16 season. He was thought of as France’s answer to Gianluigi Donnarumma when Toulouse anointed him their starter, a phenom who would go on to reach the highest levels possible from the goalkeeper position. Unlike Donnarumma who’s gotten to play on some decent Milan sides, Toulouse have been bad during his three seasons as a starter which made it a bit harder to assess his true talent level, but considering he was a teenager being asked to man the sticks for a French club in a big five league, he mostly held his head above water. That, at least, should give you a bit more confidence about Lafont’s future prospects.
A summer move to Fiorentina represented the next stage of Lafont’s career. He'd now be at a club that could provide more defensive stability and not ask its keeper to put out quite so many fires. That’s been the case through 12 games. Fiorentina are fifth best in expected goals conceded and 8th best in shots conceded. It's one thing as a defense to be good at either suppressing shot volume or limiting shot quality, but being good at both things is a recipe for a very sturdy defense, which has been the case for Fiorentina this season under Stefano Pioli.
Fiorentina defend with a man marking approach across the pitch, a method which is especially pronounced when they’re trying to apply pressure higher up. When the ball is played back to the keeper, you'll often see Giovanni Simeone make an angled defensive run to take close down the ball while taikng away one of the center-backs as a passing option. Once the ball is circulated to the flanks, it triggers a pressing action where there's pressure applied to the man in possession near the sidelines and all that could be had is a long ball to the middle third. Fiorentina have even been able to leverage this into potential goal scoring opportunities through misplaced passes from the wide areas.
Fiorentina's man-marking hasn't been quite airtight. There'll be instances when Fiorentina players are trying to switch man-marking duties, particularly if the opposing goalkeeper rolls the ball out quickly, and there's a bit of a delay as everyone's trying to figure out who's supposed to mark which player from the opposition. That can lead to opposing players being free in the middle and having enough airspace to receive a pass and dribble forward. The good news is that Fiorentina have recovered well in these instances and turned potentially dangerous situations into low efficiency shots, which is a win for the defense all things being equal. 
Fiorentina have been quite good defensively and while they haven't necessarily been elite on that end, they've certainly provided a more stable environment for a goalkeeper like Lafont than what he experienced at Toulouse. Because of Fiorentina’s defense, it’s meant that Lafont hasn’t had to face the same high volume of shots he did last season. Last season, Lafont faced the ninth most shots on target in Ligue 1 among starting goalkeepers. This season, only Donnarumma and Wojciech Szcesny have faced fewer shots on target than Lafont.
We usually talk about shot stopping ability from goalkeepers when they’re on clubs that are conceding shots on target at a higher than average volume, and their performances in goal are propping up a leaky defense. David De Gea is an example of this as he’s been the biggest reason why Manchester United haven’t been a total catastrophe. Lafont is an example of a goalkeeper making a good defense even better. Using Statsbomb’s post-shot expected goal model, Lafont’s expected save percentage from the shots he's faced when accounting for placement of shot is 73.2%, which is the 5th highest mark in Serie A. This makes some sense: Fiorentina allow few high quality shots when looking at pre-shot xG, so it stands to reason that they’ll have a better chance of limiting the shot placement from opponents that can be captured in a post-shot xG model and have an above average xSV%. Even with that high xSV%, Lafont has vastly out performed with a save percentage of 80.6%, which is 3rd best behind Luigi Sepe and Samir Handanovic, and only Sepe and Handanovic have outperformed their xSV% by mmore than Lafont's 7.4%.
Now it’s important to note that Lafont’s only faced a sample of 30 shots on target as Fiorentina’s starting goalkeeper, so it would be a bit reckless to suggest that he’s going to be able to maintain his impressive form over the rest of the season. He was basically around average when it came to his shot stopping last season in Ligue 1, with a 70.2 SV% and a 70.7 xSV%. Something that’s interesting when looking at some of the shots that Lafont has faced is that Fiorentina have done a decent enough job in getting a man in front of the shot taker to make it a bit harder on the shooter to place his shot into the corners. These are still really good saves that Lafont made, and it highlights his quick reflexes, which is what helped Lafont gain much notoriety in France.
Lafont's distribution has not been quite as sparkling as his shot stopping, but it's still been pretty good, especially given his reputation coming out of France as a sweeper keeper who is a capable distributor. His pass% of 67% is nothing remarkable but what's notable is that his pressured pass% of 78% is joint top with Luigi Sepe. Given that Lafont has only been pressured on 5.8% of his passes, which is the 5th least mark in Serie A, it could just be that his passing under pressure drops off just a tiny bit if teams start to hurry him a bit more as the season progresses. 
Alban Lafont's first season in Italy has gone about as well as one could hope for when Fiorentina spent €7m over the summer for his services. Playing on a good defensive side to begin with, his shot stopping has made them even more formidable. His distributions has shown promise, and there's even been instances where Lafont has made aggressive plays as a sweeper keeper to bail out his backline. It's fair to expect a little bit of regression with his shot stopping and ability to pass under pressure, but it's clear that Lafont has given a very good account of himself in his debut season in Serie A.