Moody's Investors Service has issued a high-quality rating on $27.5 million in bonds to be issued by the city of Worcester to fund a new ballpark for the PawSox. It's the first stage in funding the new facility for the PawSox's planned move to the city.

The credit rating agency says the city's growing tax base bodes well for taking on more debt, but there are some caveats.

Worcester already does have a lot of debt — more than $750 million worth, and Lehman says the danger is that the projected $100 million cost of the ballpark could interfere with funding services for residents by adding to the already large fixed cost of the city's debt.

"The risk is that the development does not pan out as they expect it to, and it doesn't generate the new revenues needed to cover that debt service," said Nick Lehman, senior analyst at Moody's.

Lehman added that Worcester's unfunded pension liability — which amounts to more than $460 million — is a big long-term challenge.

"That burden is something that we assess and pay close attention to in trying to determine the overall credit strength," he said.

But the rating agency says a strong local economy and responsible management by city government mitigates these risks. And, the city is expecting revenues from the ballpark and surrounding development to balance the books on the additional debt it's taking on.

Moody's said in a statement that it expects Worcester's tax base to continue growing as its planned development projects move forward. The bonds will be issued Oct. 31.