It's easy to say Chelsea "should've kept" those players but what if they didn't want to stay and fight for a spot? Lamptey and Livra both refused contract extensions because they didn't want to stay in the hope that Reece James got injured.
I'd certainly have tried harder to keep Guehi and Tomori though, not even taking into account the unforceeable reason we lost both Christensen & Rudiger, which made the decisions to let them both go look a million times more stupid.
Both Colwill and Lamptey can't get a sniff of a start at Brighton by the way.