Well, most of these folks were officially rookies in 1978, but baseball-reference.com lets me search easily by debut year, so that's what we'll go by. Listed by career Wins Above Replacement (baseball-reference.com version) here are the top players who broke into the majors in 1977 and the team the broke in with:
| Player | Team | WAR |
| Lou Whitaker | Tigers | 69.7 |
| Alan Trammell | Tigers | 66.9 |
| Eddie Murray | Orioles | 66.7 |
| Jack Morris | Tigers | 39.3 |
| Lance Parrish | Tigers | 35.7 |
| Terry Puhl | Astros | 26.1 |
| Mario Soto | Reds | 25.8 |
| Floyd Bannister | Astros | 24.2 |
| Bob Stanley | Red Sox | 21.5 |
| Rick Honeycutt | Mariners | 19.4 |
| Ken Oberkfell | Cardinals | 19.1 |
| Jim Clancy | Blue Jays | 18.6 |
| Ed Whitson | Pirates | 18.4 |
| Gene Richards | Padres | 17.4 |
| Steve Kemp | Tigers | 17.0 |
| Bump Wills | Rangers | 15.1 |
| Dave Rozema | Tigers | 14.8 |