Extending Masyn Winn doesn't make sense...yet.
Masyn Winn has been one of the best players on the Cardinals this year. He's accumulated 2.6 bWAR in just 73 games, he has a 113 OPS+, and his defense has been stellar for the most part. He's committed 10 errors, but his plus-plus arm has saved plenty of runs already. Winn's combination of offense and defense that he's put on display so far has been admirable.
However, Winn has barely eclipsed 100 career games. Several young players have received extensions before playing as many games as Winn has (Colt Keith, Corbin Carroll, Michael Harris II, to name a few), and some of those have already been somewhat regrettable. Mind you, we're talking about players who haven't even hit 25 years old yet, though, so their fortunes could change quickly.
Masyn Winn isn't yet 23; after this year, he still has 5 more years of team control left with the Cardinals. They would be wise to wait on signing him to see if he can replicate this success in his second full season. His price tag would go up rather quickly if he can be an above-average batter while providing fantastic defense, but that's the price the team will have to pay.
Winn isn't to this level yet, but the Kansas City Royals waited to sign their superstar, Bobby Witt Jr., until this past offseason to ensure that he was as good as advertised. The Cardinals should do the same with Winn. He's likely to go to many All-Star games and receive multiple Gold Gloves. The Cardinals should absolutely extend Masyn Winn, but they should wait a little longer to make sure his success early this season isn't a facade.