The duo have both featured for Louis van Gaal’s new-look side this season, with Herrera currently recovering from a fractured rib.
And former United midfielder Butt was full of praise for the duo following their arrivals at Old Trafford.
“They’ve both settled in really well,” Butt told ManUtd.com.
“Ander has been unlucky with some injuries but he’s scored a couple of goals and has looked positive and calm on the ball.
“Daley has come in and helped to shore things up – he’s probably one of the only, if you like, natural sitting midfielders that we have.
“Fletch [Darren Fletcher] always likes to get about the pitch and get forward, while Carras [Michael Carrick] is more of a passer and dictator.
“Daley is very much a protective player, but he can pass the ball as well. He’s looked strong and comfortable.”
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