Normally, teams non-tender players because they don’t want to pay them what they anticipate they would receive in arbitration. However, all four of these players are pre-arbitration, which means they would be on split contracts and would make close to league minimum in the majors.
So why, you may ask, would the Rangers non-tender them, rather than simply waive them and try to outright them?
If a team puts a player on waivers, another team could claim that player. Teams will often claim players for the express purpose of turning around and putting them on waivers in the near future, for the purpose of trying to outright the player, like the first team was trying to do.