2 things really ..
First. The game changed between him banging in goals for fun at Huddersfield first time round and when he signed for Boro .. forwards needed to be more than an out-and-out scorer and needed to be a more rounded player with contributing to the build up being just as important as scoring .. and it seems he's just not been able to do both the last few years.
Secondly. Aitor didn't want him .. maybe for the reason above .. or maybe because AK wanted to bring HIS players in instead of recieving "gifts from the owner" .. Also, see Stewie Downing
First. The game changed between him banging in goals for fun at Huddersfield first time round and when he signed for Boro .. forwards needed to be more than an out-and-out scorer and needed to be a more rounded player with contributing to the build up being just as important as scoring .. and it seems he's just not been able to do both the last few years.
Secondly. Aitor didn't want him .. maybe for the reason above .. or maybe because AK wanted to bring HIS players in instead of recieving "gifts from the owner" .. Also, see Stewie Downing