Which player has played great, "winning" tennis for a long period of time. This time period should be from about six months, and can go up to as long as you want. Post titles won, players defeated, and whatever else you may think was amazing about this span of winning tournaments.
Arantxa Sanchez-Vicario, before she became Number One, played extreme, high-quality tennis in the early 90s. From Sydney '91 to Philadelphia '92, she compiled a 117-30 (.796) record and won three titles (Washington '91, Miami and Canada '92). Out of the 33 tournaments she played, she lost before the QF only once. She reached the SF of 28/33 tournaments. Her hero, Chris Evert, would be proud of her consistency.
From Miami '93 to Oakland '94, Sanchez-Vicario compiled a 130-19 (.872) record and won 12 titles, two of them Grand Slams. Sanchez-Vicario reached 28 SFs of the 31 tournaments she played. Remarkable consistency.
Although not necessarily known for her consistency, Steffi Graf was a paragon of consistently good performance between 1986 and 1990. After losing to Hana Mandlikova in the quarter finals of the 1986 French Open, Graf reached at least the semifinals in the next 56 tournaments she played. The player who finally ended that streak was Mandlikova's protegee, Jana Novotna, in the last eight of the 1991 Australian Open.
Of the 56 semifinals that Graf played between July 1986 and November 1990, Graf only lost five - Navratilova (1986 US Open), Sabatini (1988 Amelia Island, 1990 Slims Champs), Shriver (1988 Slims Champs), Garrison (1990 Wimbledon). In the 51 finals that she played, Graf won 42. Her nine losses were against Navratilova (1986 Slims Champs, 1987 Wimbledon, 1987 US Open), Sabatini (1988 Boca Raton, 1989 Amelia Island, 1990 US Open), Sanchez Vicario (1989 French Open), and Seles (1990 Berlin, 1990 French Open).