Maxi's a good example for us that worked out. Almost 30, coming to a new league, had an ACL tear too a few years before joining us. Clearly wasn't at the highest level he had been at when at Atletico but still a really good addition to the side. His footballing brain outweighed any of the age woes. However, there's a caveat because we didn't spend much to get him. It was a very good deal at a difficult time for our side. With the wages someone like Thiago is getting, you'd expect him to perform at a very high level, but he'll have adapting to do.
That being said, it's always interesting to see how Klopp could evolve the side. During the 2017-18 season, if someone said we'd be CL winners in 2019 and Prem winners in 2020, I don't think anyone would be thinking "yes, our full-backs will combine to get 20+ assists in all comps, no worries." Werner could've been part of a rotation/long-term front 3 transition but also an opportunity to try different tactics, possibly getting all 4 attackers on at the same time (back to an old 4-2-3-1 maybe?). Klopp likes versatility in his players, and he and his coaching staff are also open to new ideas over time. While the focus is on an attacker to help with the front 3 and left-back cover, the message seems to be that given the uncertainty, Liverpool will be looking for opportunities that could come up. Normally, contact with agents, targets, negotiations, etc are pretty set over time, but given all the uncertainty, could see deals/opportunities pop up. Would be curious how it all shapes up. Thiago doesn't seem like he'd be a top target, but if it means we can improve our side by adopting new tactics/ideas, it could be interesting. Given the number of games we tend to play and the opportunity to pick up domestic cups too, it won't prevent someone like Jones from getting game time any way. Coaches have done well to give some of the youth chances in a top side, and they can continue to do so whilst having more depth for deep runs in multiple competitions.
Front 3 and LB cover still seems like top priorities though.