Are the Glazers, the enigmatic family that owns Manchester United and the Tampa Bay Buccaneers, strapped for cash? While most of the financial manoeuvrings of the Glazers are hidden from public view, circumstantial evidence suggests that problems may exist. Not the least of which is their decision not to pay down their Manchester United debt, which has a double-digit interest rate.

Questions about their ongoing viability are openly discussed in Tampa Bay, where fans of the gridiron team fume as they feel the Glazers did not spend to make the team competitive for next season. While Manchester United chase four trophies, Tampa Bay's parallel universe is bleak. Las Vegas bookmakers reckon they will have a losing 7–9 season this autumn, and no play-off prospects, after two mediocre campaigns of 9–7.

The family rarely discuss finances but Joel Glazer was forced to explain their rationale regarding Tampa and new players. "Sometimes you can throw money at a situation and it can get you in trouble. We are big believers in building a sustainable franchise that is going to be in competition for many years for the ultimate prize," he said.

Those words are not sitting well with Tampa fans. There is a salary cap in the NFL, which is in place to try to ensure that all 32 teams can be competitive and have the same chance of reaching the Super Bowl. This year's salary cap is $127m (£83m) and at the start of the annual free-agency signing period in late February the Buccaneers organisation had nearly $62m of cap space, the most of any team in the country.

The Glazers had made some stunning decisions in the few weeks between season's end and the start of the free-agency period. They fired the general manager Bruce Allen, the Super Bowl-winning head coach John Gruden and five high-salaried veterans, including arguably the franchise's best ever player, the linebacker Derrick Brooks. Brooks's career in truth is winding down but his supposed replacement, Cato June, was released. The household-name receivers Joey Galloway and Ike Hilliard together with the popular running back Warren Dunn, all of whom are near the end of top-notch careers, were also let go as the management went for lower-priced younger players.

High anticipation of new players rapidly turned to frustration as the Buccaneers were outbid for the signatures of several big names and an analysis by ESPN is that the Bucs have taken a step or two backwards in the quality of the team. The recent signing of several rookies via the annual draft has done little to appease the naysayers. With the best players in free agency now elsewhere the Buccaneers still have approximately $30m in salary cap sitting unspent, the most in the entire league.

Salary-cap space and actual cash are of course completely different and internet message boards in Tampa and beyond are full of speculation about the Glazers' finances. According to Jim Flynn, the editor of Pewter Report, which claims to be the largest independent site following the team, there is no hard evidence although the signs certainly indicate they might be hurting.

"I can tell you there are a lot of frustrated fans," said Flynn. "Once the rumours started to leak and pick up some momentum – that there were cash-flow issues – I think a lot of fans started to buy in, and now it has gotten to the point where some fans are making more of it than should be made of it."

Flynn said Tampa fans realise the purchase of Manchester United was a huge deal for the Glazers but only now with the lack of free-agency action and the structuring of contracts that have low up-front payments are they linking the events.

Fans are voting with their wallets. The team had a 145,000 waiting list for season tickets in 2007. That list has disappeared and the Bucs now say anyone who wants a season ticket can buy one. There is even talk that Tampa games will not sell out, something that has not happened for years. Indeed, the team will travel to London for one of their eight "home" games to play the New England Patriots at Wembley.

In the UK, the Guardian recently reported that Manchester United's massive debt was being sold at a 30% discount by its holders because they believe that they may not be paid. While the intrinsic value of the Manchester United and Tampa Bay Buccaneer franchises are holding up during this recession the same cannot be said for the Glazers' holding company, First Allied Corp, which owns and manages nearly 7m sq ft of community and neighbourhood shopping centres located throughout the US.

First Allied is a private company so there is no access to its financial information but there is no doubt that shopping centre owners are being badly affected by the economic downturn, with retailers shutting down in droves. New stats show the vacancy rate at neighbourhood and community shopping centres rose to 9.5% in the first quarter of 2009 from 8.9% the previous quarter and 7.7% a year ago, according to the research company Reis. Victor Calanog, director of research at Reis, believes the situation will get worse before it gets better. He is projecting a continued increase in vacancy for neighbourhood and community centres into 2011.

Shedding a little light on their empire, the Glazers also own a small publicly listed company called Zapata, which invests in other companies. Those investments went south in late 2008 and have continued in that direction. The company reported a fourth-quarter 2008 loss of $456,000 as opposed to a net profit of $909,000 the previous year. And for the first quarter of this year Zapata reported a consolidated net loss of $727,000 compared with a net profit of $320,000 in 2008.

Neither the Glazers nor Manchester United responded to interview requests and the Buccaneers' director of public relations, Jeff Kamis, said: "We are not going to speculate on cash-flow problems based on what a couple of fans wrote on message boards."

Certainly fans of Manchester United and the Buccaneers care little or nothing about the Glazers and any cash-flow woes. They want only to be assured that their teams will be contenders in the coming season. While Manchester United could wrap up the Premier League title this weekend and have a Champions League final to look forward to, there is no such assurance for Tampa fans.