Lots of great candidates today. Let's go.
5. Eduardo Perez (0.5 WAR)
Today's first entry is a legacy guy, as Eduardo is Tony Perez's son. The Reds picked him up in 1996, and he played in 106 games in '97, OPSing .796 along the way.
He's another one who was included in the Griffey deal. Antonio Perez was included in the Griffey deal, not Eduardo, although Eduardo did play for them after his Reds tenure.
4. Gene "Junior" Thompson (4.3 WAR)
Junior Thompson played for the Reds from 1939 to 1942, and was another starter on the World Series winners from 1940. He went 16-9 that year with a 3.32 ERA. His last two years weren't as productive as his first two, but his next 3 made up for it as he fought in the U.S. Navy in WWII. He returned from the war and pitched two more seasons for the Giants.
3. Dave Parker (4.7 WAR)
Cobra! Parker played for the Reds from 1984 to 1987, signing with the team during his first stint as a free agent at age 33. He was slightly past his prime at that point, but still very productive, hitting .281/.334/.469 in his Reds tenure. He made All-Star teams in '85 and '86, and was the runner up in MVP voting in '85 with 125 RBI.
2. Joe Nuxhall (15.5 WAR)
I know, he won #41. But he was even better as a #39. He wore it from 1952 to 1960, but is better remembered for another number so we're leaving him here.
1. Aaron Harang (18.2 WAR)
Harangatang spent 8 seasons with the Reds, and was as good as any Reds pitcher in the last decade. 2006 and 2007 were the prime of his career, as he recorded strikeout totals over 210 in both of them, his best two seasons of his career. He was also a workhorse for the most part, pitching over 200 innings in 3 straight years before injuries started taking their toll. He pitched for the Mariners and Mets last year, and will try to make the Indians this year. Hope he makes it.