Joseph Gordon-Levitt left the series during the final season, so the storyline has his character Tommy away at college.
dʒˈoʊsəf ɡˈoːɹdənlˈɛvɪt lˈɛft ðə sˈɪɹiz dˈʊɹɹɪŋ ðə fˈaɪnəl sˈiːzən, sˌoʊ ðə stˈoːɹilˌaɪn hɐz hɪz kˈæɹɪktɚ tˈɑːmi ɐwˈeɪ æt kˈɑːlɪdʒ.