The Atletico Madrid striker won the World Cup Golden Ball last week.
United reserves coach Solskjaer told the Manchester Evening News: "Diego Forlan was a very good player even when he was here. He has always been a good player.
"Ruud van Nistelrooy was here at the time and scoring a lot of goals so it was tough for anyone coming in.
"We played with Paul Scholes just behind Ruud and it was a productive way of playing. I also played with Ruud up-front as his strike partner.
"It meant the chances for Diego were limited. When you have that kind of competition it can come down to luck. You may have quality but there has to be a certain amount of good fortune as well.
"Sometimes you can just be at a club at the wrong time for you.
"But Diego was a great striker. He could score with right or left foot and had great movement and great touches. The gaffer has always said he is a great player but because of circumstances it just didn't work out for him at United.
"But he has gone on to have a great career and hopefully Javier (Hernandez) will also have one but hopefully it is at Old Trafford this time. He certainly looks to have the quality anyway so let's hope that everything else falls into place for him."