Ings has 9 goals in the 32 games this season, Immobile has 10 from 28. If you are discounting the good season Immobile had in Seire B then you should do the same for Ings in the Championship last season. Meaning while Immobile has had one great season for Torino (a one off as you say), Ings has never had a season where he has been anywhere near that level.
Id take Hernandez on a free, but hes a bit part player and it will never happen anyway.