Not everyone in baseball is happy with prospect Jon Singleton's historic five-year, $10 million contract with the Houston Astros.

Bud Norris, a former Astros right-hander now pitching for the Baltimore Orioles, blasted the deal Tuesday on Twitter, just hours before Singleton homered in his major league debut.

Sorry but this Singleton deal is terrible. Wish the Jon listened to the union and not his agent. - Bud Norris (@BudNorris25) June 3, 2014

Mark Mulder, a nine-year veteran who was in camp this spring with the Los Angeles Angels before rupturing his Achilles, also critiqued the deal via Twitter:

Just saw contract this #astros prospect signed. Either he doesn't believe in himself to be great or he has a terrible agent who wants the 4% - Mark Mulder (@markmulder20) June 3, 2014

Singleton's new contract -- which includes three club-option years that could increase his payout to $30 million over eight years -- is the first extension to be signed by a drafted prospect with no major league service time.

The deal replaces a one-year contract Singleton signed in February that called for a $500,000 salary while in the major leagues and $40,750 while in the minors.

Critics of the contract will point to the fact that Singleton, 22, potentially sacrificed greater future earnings via free agency or arbitration by taking immediate security with this deal. If the Astros pick up all three options, he won't be eligible to test free agency until he's 30.

Moreover, it could set a precedent for teams and their prospects going forward.

But Singleton's case is somewhat unique, too.

Acquired from Philadelphia in the 2011 trade for Hunter Pence, he was suspended 50 games last season for a second violation for a drug of abuse. Singleton told The Associated Press in spring training that he has an addiction to marijuana and had spent a month in a rehabilitation center last year.

Singleton immediately upgrades a Houston first-base contingent that ranks last in the majors with a .181 batting average and a .561 OPS. Jesus Guzman and Marc Krauss have logged the bulk of the at-bats at first base for manager Bo Porter.

ESPN's Keith Law ranked Singleton the No. 78 minor league prospect in baseball before this season, down from No. 32 in 2013.

Krauss was optioned to Triple-A on Tuesday to make room for Singleton.

ESPN.com's Jerry Crasnick and The Associated Press contributed to this report.