The Red Devils activated Herrera’s buyout clause at Athletic Bilbao to bolster their midfield ahead of Louis van Gaal’s first season in charge, with the 24-year-old signing a four-year deal.
United had been linked with both Pogba, who left the club as a 19-year-old in 2012, and Real Madrid-bound Kroos but Butt, now a coach at the club, admitted such players are more difficult to land.
“You can all talk about Paul Pogba or Toni Kroos or whoever but these kind of players are not easy to get,” Butt told the Manchester Evening News. “So you have to widen your net and Herrera is a bonus.
“He is at a level where he can play at a club like Manchester United and given a bit of time he can excel. He can become a star player for us.
“I do think he has the ability to do that. He can become a big influence on our midfield. You will have to be patient with him. You cannot expect miracles from him straight away just because there is a big price tag attached.
"That’s not the lad’s fault. It is just the way football has gone. That’s between the two clubs and shouldn’t be allowed to put pressure on him.
"Given the time and the chance to develop, he can become a very good player. We think he can achieve very good things. It is a great signing for United and I am very pleased. I am sure the fans will take to him.”
Butt hopes Herrera’s main contribution will be to improve the level of United’s play in possession as they continue to search for Paul Scholes’ long-term successor following the playmaker’s retirement last year.
“[Herrera’s] ability to pass and keep the ball is great,” Butt added. “You can see the Spaniard in him because they are always so comfortable on the ball.
“They can take the ball in any situation. It doesn’t bother them. They want to keep the ball moving and play things simple. He looks like he will be a very good player for the club.
“He was at the level where you just had to take note of this player because there are not many top midfielders you can get, in my opinion.”