People sometimes assume that a non-tendered player must be terrible. After all, their reasoning goes, the team owning their rights could keep them at arbitration pay rates – which are generally held to be substantially less than fair market value – but instead chose to release them for no return at all.
This is sometimes true, but like most things in baseball the truth is more complex. A player could be coming off an injury, or a bad year, or just not fit in with a team’s plans. Or the team could believe that they can release the player and then re-sign him at a lower rate.