More deals are planned and the capture of Sligo striker Mark Quigley - who also had a previous spell at Rovers - should be completed within days with a deal for Sligo keeper Gary Rogers also in the pipeline. That's bad news for Sligo but a good sign for the Hoops who finished the season without a trophy and failed to qualify for Europe.
Fans at Rovers demand success but McGuinness has pleaded for patience as Croly attempts to put his own stamp on the side. "This is a rebuilding process and the supporters will have to be patient," McGuinness told the Herald.
"We have a new manager, some new players signed already like myself and a few more new faces on the way, but the team will need time to settle and gel together as a team.
"That's not to say that we're not ambitious; I am very ambitious and I want to win things at Rovers but it won't happen overnight. The squad needs changes after what happened in the season just gone and Trevor will bring in some top quality players, but the supporters have to understand that it will take time," added McGuinness.
"We're not in Europe next season and that is disappointing but, to me, the league is your bread and butter, the trophy you aim to win every season and Europe is a bonus. It's our job now to make Rovers a possible league-winning side."
The former U-21 cap says he has unfinished business at the club from his two-season spell there in 2004 and 2005, as he picked up major honours at his other clubs - Bohemians and Sligo - but won nothing in his time with the Hoops.
"I do want to win more things and I hope that can happen at Rovers," he says. "I have played for the club so I know the background, I know the demand for success and I hope the squad of players we'll have in 2013 can deliver."
McGuinness won league and FAI Cup medals in his time at Sligo but he admits it was a wrench to leave the Showgrounds. "I had a brilliant time there and I have nothing but good things to say about the people in Sligo but I decided to move on for family reasons," he says.
Chambers, who was at Rovers in the 2010 season, is also pleased to return.
"I'm glad it's all done and I'm delighted to be back at the club. When Trevor said he wanted me to join him here, it was a very easy decision for me to make," says Chambers.