The Republic of Ireland striker signed with the MLS outfit from Championship club Wolves on Friday but will not join until July 1.
Until then, the goalless Rapids will have to continue on without the 31-year old attacker but when he does finally arrive, Mastroeni is confident he will be a success in Denver.
"Kevin's track record speaks for itself," Mastroeni said in a team statement.
"We are confident that he will add quality to the side with his own play but his intelligence, experience and professionalism will also bring the best out of others.
"As we continue to build for the future, Kevin will help us maximize our potential both on and off the field."
The sentiment of Mastroeni was echoed by Rapids technical director Paul Bravo who expects Doyle to make a difference to the club.
"We believe he can bring a great deal of experience to our squad having played in the Premier League and at the highest level of international football," Bravo added.
"We really believe that he will be a difference-maker for us over the course of the next three seasons. His ability to help us in all areas of the offense will be invaluable."
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