According to various sources, former Astros and current Marlins pitcher Jarred Cosart has outed himself by mentioning on Twitter that he gambled on sporting events, and specifically on college basketball's March Madness.
Cosart, no stranger to Twitter controversy (just Google "Jarred Cosart Twitter" to see what I mean), apparently admitted via Direct Message (DM) to a bookie or gambling advice expert that he placed a large bet on a sporting event. The recipient of the DM went public for reasons unknown with screenshots of the conversation. Speculation about this being a hoax were seemingly addressed when Cosart's now-infamous Twitter account first went private, and then was shut down completely.
MLB rules do not specifically prohibit betting on other sports, unless one is to construe the generally-worded "Other Misconduct" as indicating that any sports betting is not "in the best interests of baseball". So it is unlikely that official punishment is made in this case, if it's even provable.
However, there was already speculation among bookies (see previously linked article) that Cosart may be throwing some games -- speculation based on strange run prevention stats for his career in the first innings of games. But there is no evidence that this claim has merit or is any more than the irresponsible musings of the internet, and should be treated as irrelevant unless more information comes to light.
Regardless, this is yet another in a string of examples showing Cosart's immaturity, a major factor that was rumored to drive his trade to the Marlins in return for 3B Colin Moran, CF Jake Marisnick, P Frances Martes, and a compensatory draft pick. On the surface, and from the outside, this instance is another feather in Houston's player evaluation cap. Perhaps Cosart will have a long and successful career as a MLB starter as scouts once thought he would. But is the headache worth it? Each successive occurrence of poor judgment off the field requires a reevaluation of his risk and likelihood to succeed on the field as well.
10:10 AM Central Time: Apparently, MLB is investigating Cosart's ties to sports gambling. Cosart is also claiming that his account was hacked to frame him, and that he would never bet on baseball (which, it should be noted, was not implied by the Twitter conversation).