Middlesbrough coach Agnew has watched his old club's progress under Bruce and he is convinced they will improve again next season.
"It's great to see Sunderland doing well again," he told the Sunday Sun.
"The North East is a special area for football and I think that when you've played for one of the clubs, you're always going to keep an eye on them and how they are doing.
"Their mid-season form wasn't great - they lost a bit of form for whatever reason - but it is good to see they have finished strongly and finished in a healthy position.
"It's a terrific club with terrific support and I'm sure they will strive to push on next season - and I see no reason why they can't break into that top 10."