If by "mushy" you mean mealy, some varieties are meant to taste this way because they are geared towards making sauce, not eating raw.
If they're mushy because they're overripe, try picking a few that are only just starting to turn color, put them in a paper bag and close them up for a few days. They should turn color and perhaps the texture will be more firm. It's worth a shot!
Other than that, all I can say is plant a different variety next year