I'm not aware of any articles that mentioned us taking him to fill a hole in defence, in fact I always had him pegged as a forward to help take over from Pav which is effectively what every draft expert expected of Brennan (to be a key forward at AFL level).
Most if not all of the messaging out of the club spoke about Brennan being a forward for us and that's one thing I don't think you can really criticise RL for. Cox was a rising star as a forward and had a fantastic output as a young key position forward. All the stats point to him being a gun in the role and I'd expect him to perform similarly when handed jobs in defence.