David Glass should know his credibility is on the line. Right now. The next 10 days could determine his team’s future, and with it his legacy. He should know that a decade of promises and six years of changed ways will be proven fraudulent if he continues pulling the false-economy parking brake that diminishes his team’s ability to improve at such a crucial point.

Glass has always maintained that he would spend more money, even be willing to take a relatively small operating loss at the right time, if it meant securing a competitive team.

Well, the time is here. Nobody ever built a winner exclusively through the farm system, so Glass’ apparent insistence on capping the team’s payroll at around $70 million is as ridiculous as it is self-defeating. It is an assault on common sense.

The Royals are loaded with young, improving position players and a bullpen stocked with power arms. They need one frontline starting pitcher to be a legitimate contender in the weak American League Central, and to get that they need some money from the boss.

If Glass doesn’t step forward now — if he really limits the Royals to $70 million when an extra $5 million or $10 million might make a huge difference — then everything he’s said about wanting to win is a lie. He will be despised beyond anything he’s dealt with so far. Nobody will be able to defend him.

If Glass sticks with his limit, then he’s holding the team back with short-sighted and misguided priorities. If he lets relative nickels keep the Royals from assembling the best roster possible at this crucial time in their growth, then fans should be offended.

The days of Glass crying poverty need to be over. The no-money Rays just signed Evan Longoria to a $100 million extension, nearly twice as much as the Royals have ever guaranteed a player. Teams in similar markets — Cleveland, Cincinnati, Minnesota, etc. — extend payrolls past $80 million for the right situation. The Royals are now in the right situation.

They’ve gone this high or higher before, and with a less realistic chance of winning. That was before a new national TV contract that makes every team richer — a $75 million payroll would’ve ranked 19th in baseball in 2010; last year it would’ve been 24th.

Baseball’s economics — particularly the bad local TV contract the Royals willingly entered — are still tilted toward bigger markets, but Glass doesn’t have to take a big loss to build a legitimate contender.

The Royals had baseball’s lowest payroll in 2011, which was the smart baseball play as they fielded 16 rookies. Also, Gil Meche walked away from the last $12 million of his contract.

But the franchise has also made more than $90 million profit since 2006, according to Forbes. Especially with new baseball restrictions on amateur spending, Glass and the Royals have saved more than enough the last few years to extend the payroll to at least $75 million and as much as $80 million.

At that point, it’s on general manager Dayton Moore to make the right decisions. If he doesn’t, Glass should hold him accountable.

If, somehow, this means the Royals operate at a relatively small loss for a few years, well, Glass’ $96 million purchase is now worth an estimated $354 million. His stated goal of breaking even on the team is safe.

Nobody expects the Royals to sign Zack Greinke, who might command as much as $150 million as a free agent. But the fact that Glass’ governor on spending has put Anibal Sanchez out of play is silly. That it’s put obstacles in front of acquiring even lesser pitchers is egregious.

But, still, the Royals are apparently up against this made-up spending limit, with Moore saying that any payroll additions will require proportionate subtractions. The payroll for their 25-man roster, as their roster is currently constituted, projects to be $66 million to $67 million. The Royals currently have $50.6 million committed in guaranteed salaries to 10 players on their 40-man roster.

Even on a roster with some fat — the Royals really shouldn’t pay Luke Hochevar $4.4 million, for instance — this is an unnecessary hurdle for a franchise that already has too many of them.

Fans have been patiently waiting for this roster to mature, literally since the day the current stars were drafted or signed. For Glass to stunt that maturation with an artificial spending limit below the line between profit and loss is indefensible.

Teams have won divisions with lower payrolls than what Glass is apparently calling for, of course. But requiring miracles is not a good strategy. The Royals need some help from the man who’s long said he’d provide it.

That man’s credibility is on the line. A fan base waits.