Alonso struck from long range to hand his side all three points, continuing their good form that has seen them go eight games unbeaten, winning their last five.
"The good thing about Marcos is he's a willing lad. He turns up with an attitude that he wants to get better and somebody like that is always going to get better," said Freedman.
"He's the kind of guy who plays with a desperation to win at all costs. Sometimes he's naive in his defending because he's so desperate and that's what you've got to learn.
"But I think him, young Jay Spearing and the captain Kevin [Davies], the way they're showing a desire to win football matches is spreading throughout the squad and that's the pleasing thing as a coach."
The win puts Bolton within three points of a playoff position in the Championship.