The Astros did not sign first-round pick Brady Aiken or fifth-rounder Jacob Nix, reports MLB.com’s Jim Callis (on Twitter). Aiken becomes just the third No. 1 overall pick ever to not sign, per Callis (Twitter link). Nix had previously been reported to have agreed to terms, which Evan Drellich of the Houston Chronicle reports (on Twitter) was by way of a verbal agreement.

The two young pitchers are both reportedly advised by Casey Close. Houston also ultimately failed to reach terms with another well-regarded arm, 21st-rounder Mac Marshall, Callis adds. That confirms Marshall’s own announcement that he would instead attend LSU.

The Astros will receive the No. 2 pick in next year’s draft, Callis further notes, meaning that Houston did at least offer Aiken 40 percent of his slot value ($3,168,840), which Aiken did not accept. In fact, Houston ultimately upped its offer to $5MM, according to Jon Heyman of CBSSports.com (Twitter link). “We tried to engage Casey Close three times today,” Astros GM Jeff Luhnow tells Evan Drellich of the Houston Chronicle (via Twitter), but “there was no interest.” Ultimately, the team made three offers today, Heyman tweets, the second of which came with 30 minutes left on the clock. The final, $5MM offer was made with just five minutes to go. Aiken did not counter any of the offers.

Aiken and the Astros had reportedly agreed upon a $6.5MM bonus, with Aiken heading to Houston for his physical and an introduction. But things took a turn when a dispute arose over the interpretation of MRI results regarding Aiken’s elbow.

In many ways, the news represents a disappointing result for both Houston and the two players who had been expected to sign. The club will of course have an opportunity to choose another top-end player next year (along with the team’s regular first-round choice, which should be a good one), but will have to wait to get that player started. And Houston will miss out on a pitcher who Luhnow himself called the “most advanced high school pitcher” he’s even seen. Not only that, but the team has now foregone the opportunity to sign Nix, and could even face some form of grievance proceeding as a result of the handling of Nix’s negotiations.

Meanwhile, Aiken will need to perform at rather a high level to beat the $5MM that he ultimately was offered, and will need to wait some time for a check to cash. It is not yet clear where he will go, though presumably he will either enroll at UCLA (where he was committed) or else choose the junior college route. Of course, the very public nature of the recent negotiations regarding Aiken and Nix might conceivably have some ramifications for those players’ future collegiate eligibility, which would obviously be an unfortunate byproduct of a difficult situation.

Needless to say, the situation has led to quite a bit of chatter around the game. As MLB.com’s Jim Callis explains, speculation arose that Houston was hoping to drive down Aiken’s price in a bid to make a last-minute run at Marshall, who had long before said he was going to college. Of course, it was never certain that such a possibility was realistic, let alone that the club would ultimately pass on the chance to add Aiken (and with him Nix) without some genuine concern.

Indeed, the apparent medical dispute regarding Aiken, and its impact on Nix, have led to indications that fallout may be yet to come. The Astros released a statement, saying that the club’s final offer was “extremely fair considering all the factors involved in this case” and insisting that the team “approached these negotiations in good faith and with the best interests of the Astros organization in mind, both short-term and long-term.”

But the MLB Player’s Association sees things somewhat differently, stating the view that Aiken and Nix were wronged. “Today, two young men should be one step closer to realizing their dreams of becoming Major League ballplayers,” said executive director Tony Clark. “Because of the actions of the Houston Astros, they are not. The MLBPA, the players and their advisers are exploring all legal options.”

Jeff Todd contributed to this post.