(CBS) The MLB Players Association has taken a strong stance against the Cubs’ decision to send prized prospect Kris Bryant to Triple-A to open the season, issuing a statement on Twitter that called it a “bad day for baseball” while also threatening litigation in such instances.

The move the Cubs made to send Bryant down is well within the rules of the collective bargaining agreement and one of the few instances in which clubs have the advantage over players. In this case, sending Bryant to the minor leagues for two weeks will allow the Cubs to control Bryant’s contract for an extra year — through 2021 instead of 2020 — because this season wouldn’t count as a full one of service time.

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Still, the union was having none of it.

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MLPBA executive director Tony Clark previously said the union would be following Bryant’s situation closely.

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Bryant hit .425 with nine homers, 15 RBIs and 1.652 OPS in Cactus League play. Bryant will be called up “sooner than later,” Cubs president of baseball operations Theo Epstein said Monday.