All i'd say is that unless Tomi's not fit enough it was a big mistake not to use him in that game - I'd have played him from the start - but I suspect his absence does mean he can't be fit, so that's not really on Arteta
We really do need to buy an LB in the summer though, we literally don't have one atm unless you count Timber and it's not totaly cleear what his number one position will be