Garrett is in his third season as coach of the NFC East side and has yet to secure a playoff berth with back-to-back 8-8 seasons.
"He's a young coach, and one of the things you've got to remember, that you should remember, is that, as a young coach, your system should be evolving," Jones told the Star-Telegram.
"There shouldn't be a system that you've hung on for years and years and years. Ernie Zampese, for instance. Jason's fresh in his evolving, as far as scheme is concerned."
The Cowboys face the San Diego Chargers this Sunday.