Judging on the number of clean sheets we've kept in the last 8 prem games (6 last season) the change in formation is helping our defence. Kolarov is one of the best attacking left backs out there, with support from Sterling he can also do his defensive work more easily. When Silva was on the left side he'd often cut into the centre of the pitch and when we lost the ball he wouldn't be able to support Kolarov.
Kolarov and Clichy are good enough in the right formation. There's no reason to panic buy any of the names we're linked with. Sandro, Kurzawa, Rodriguez are all promising players but haven't shown enough consistency to warrant the expenditure. Kolarov has looked miles better since the altered formation so I think the club are doing the right thing in sticking with what we have. It remains to be seen whether Angelino can then come in next season without going into the market.
Looks like KDB is close then... should be sorted next week ;)