They're also being signed because Souths obviously have several players on a decent salary, taking up the bulk of the cap. You can only offer what you've got left, and that seems to be only enough to attract those who are willing to take anything to get onto an NRL list, i.e., those seeking an opportunity or have had long-term injuries which the club agreed to take on and rehab.
Re those signings you've mentioned - Benji, Mansour and Host have come relatively cheap for the quality they are. Have to remember that two of them (the older boys) were after the opportunity and souths have given it to them.
Arrow - yes, he is a wonderful player, but IMO not a good signing for Souths. He is a #13 and Souths already have a superstar in that position and the club also has Hame Sele who is very good player to have in the rotation off the bench and done a stellar job in previous seasons. Yes, bring in another #13 for depth but it didn't have to be someone of the $$$ that Jai commands. I understand the talk was Cam Murray moving to the edge, but we saw last season that this team (any team) is better with Murray getting carries in the middle rather than hole running on the edge. Arrows money could have gone to another position to shore up the balance of the entire squad.
Knight had a breakout season a few years ago and is still living off the back of that I feel. Mago is a much better option in the rotation this season and I feel it was better when he was in there for a couple of games. A bit stiff to be dropped to Cup when Knight came back, but Knight is on bigger $$$, and when the execs at head office in every sport put together their spreadsheets at end of year, they want to see a big % of the salary cap on the field. I'm sure that's why Knight is getting on ahead of Mago.
Edge forward, particularly the right side, has been an issue for the Souths for several seasons now - Sam Burgess, Cam Murray, etc have been moved away from where they are most effective in the middle to plug gaps in this position. We thought Su'A would be the answer, but he seems to be in the mould of his young Broncos brethren who relish carting up the pill, but loathe defending. Let's face it, all those Broncos young talents everyone has creamed over are Pasifika boys who just steamrolled their opposition as juniors, and rarely had to defend at that level. It's a different case in the NRL. Defence IS what wins games. Marker defence, repeat effort, lateral movement, and resilience become paramount.
Keon has been a revelation and a local. Thank f**k he's come on the scene as it has given the club an option to perhaps let Su'A go if the club can't meet his demands, and Host can fill the right edge position. Keon has been excellent with the ball in his hands, but like some of the others, he's been found out a few times in defence so that is an area of his game he needs to work on.
I don't know where my post ended up going but there it is.