Sometime in May, Bill Zito, Tim Thomas’s agent, contacted Peter Chiarelli. The Bruins general manager prides himself on preparation, covering every angle, and not being caught unaware in any situation.

But Zito’s thunderclap of a message surprised even Chiarelli. Thomas, the team’s most important player, was considering not playing in 2012-13, the final season of his four-year, $20 million contract. ESPN.com first reported Thomas’s plan on Thursday.

Since’s Zito’s bombshell, when conceptualizing the blueprint of next season’s team, Chiarelli has assumed that Thomas will not be part of the roster. If Thomas sits out, the Bruins will have to carry his $5 million annual hit toward their cap number. It is the team’s third-highest cap hit after Zdeno Chara ($6,916,667) and David Krejci ($5.25 million). Thomas is due $3 million in salary in 2012-13. Chiarelli asked Zito if Thomas was seeking a contract extension and Zito told the GM that Thomas was not interested in a new deal.

“As of right now, I’m operating under the premise there is a strong possibility of him taking the year off,’’ Chiarelli said on Friday during a conference call. “We’d have to go about our business without Tim Thomas for the year.’’

There is no timetable as to when Thomas will make a final decision. The Bruins would be best served with an answer by later this month. The draft will take place in Pittsburgh June 22-23. Trades often take place just prior to the draft, on the floor itself, or upon its conclusion. Free agency opens July 1.

According to Chiarelli, Thomas cited fatigue and the desire to spend time with his family as the primary factors in his impending decision. Thomas and wife Melissa have three children: daughters Kiley and Kelsey and son Keegan. Zito did not return a message seeking comment.