Last Year's Discussion
Trea Turner is the Nats shortstop until he gets hurt, traded, or leaves in free agency. He's good. He's cheap. After a perfectly decent 2019 there were no questions other than could he stay healthy as he missed another 40 games in 2019 keeping 2018 as his only full season.
In 2020 Turner was healthy the whole way and had his best season ever. Some of that is a high BABIP but it's certainly not too high. Walk rate is good. K-rate is down. Most importantly he showed a lot more power than he had in the past. There was a little glimpse of that last year as he went from 27 2B, 6 3B and 19 HR in 162 games in 2018 to 37 2B, 5 3B, and 19 HR in 122 games. He kept improving hitting 15 2B, 4 3B, and 12 HR in last years limited season which would translate to like 40 doubles, 10 triples, and 31 homers in a full season. 31! That's big boy numbers!
Trea's defense was about how it always has been. So the loss of Rendon didn't particularly do anything.
Presumed Plan : Turner starts at SS. His back-up is any number of guys but Kieboom is probably most likely unless they sign a FA.
Reasoning on Presumed Plan : Turner last year was one of the best offensive shortstops in baseball. Even if that's a fluke of the short season he's been improving and you'd expect him to be at least better than average. And really you are hoping it's not a fluke because Soto could really use another star bat in the line-up to help him out. Seeing that power go up while the peripherals go down is very encouraging. It means it's not an swing for the fences approach that's giving him his power.
His defense has been passable for the Nats and the fans think he's pretty good.
Money wise he's still underpaid
Good, cheap, and can play the spot? This is an easy call.
Problems with Presumed Plan : Nats fans have always overrated Trea's defense. From the early years when he was good and fans believed he was great, to now where he's not good and fans believe he is. He's aging out of the role.
Hitting wise we might get be getting a little ahead of ourselves if we're thinking Trea's a star. He could be - the trends are good, he's shown flashes before - but it could also be that fluke and he could merely be a decent bat. That's a problem not for him starting but for building around him in a cornerstone of the line-up sort of way.
He does get injured pretty frequently with only ~1.5 (counting 2020) full seasons.
My take : There's no surprise here. You start Trea, but you don't quite plan around him being anything beyond a good player who can hold down SS for 140 games. You hope he's great at the plate and good in the field. Worst case he's good at the plate and below average in the field. Likely he's somewhere inbetween but even if he hits the worst case, it's not enough to make him not worth his money or not a good player.
Back-up doesn't particularly matter because since Trea is good he's going to play as much as possible. Yes, we do have to worry about injury but for the most part he's been healthy enough across the past three years so I don't think you have to take that into account. If he misses a month - oh well. If he misses more - that's not a surprise but it's also one of those things that you just have to accept. Like Max going down at anytime given his age. You can't bring in a full-time good SS to sit behind Trea. Better is making that re-sign of AsCab and then if things happen to Trea and other guys hold their ground he fills in there.
This is not a problem position.