Fair points on all those players, especially as we need them to gel quickly as 2 of them (BBD and Clarke) are definite starters at the moment while the other 2 (Cannon and Choudhury) are potential starters.
BBD: I'll agree that this signing is a bit of a risk given his lack of game time, but it's a risk worth taking as we know how good he is at Championship level, and he provides cover for our most creative player and arguably 1 of the best players in the league (if not the best), Hamer, also allowing us to possibly play Hamer in his natural CM position.
Cannon: When we subbed Campbell off and later when he was injured, we lost a significant goal threat as Campbell was the only natural goalscoring striker we had (and his absence demonstrated this), Cannon has that same natural finish which we missed while Campbell wasn't playing, 2 natural finishers are better than 1 imo, especially as Campbell (as good as he has been) has yet to play 90 minutes for us, something Cannon, Brewster and Moore have all managed this season.
Choudhury: Similar to the Cannon/Campbell situation only this one concerns Souza, we've seen how easy it is for teams to get through our midfield when Souza isn't playing (as we lack that steel and tenacity), while Choudhury isn't as good (ability wise) as Souza, he should give us that same steel in midfield that Souza does.
Matt Clarke: Might not have been our first choice for RB but last few games it's become necessary that we sign a RB ( Seriki fitness and Gilchrists loss of form), as for JJK, I'd say the jokes on Hertha Berlin as we quickly got another target in, while they're now stuck with a player who doesn't want to be there and will now leave for nothing in the summer.