Chris Evert. Her strokes match her records.
The barometer for consistency.
From Wikipedia:
"Evert reached 34 Grand Slam singles finals, more than any other player in the history of professional tennis.
[3] She holds the record of most consecutive years (13) to win at least one Grand Slam title.
[4] In singles, Evert reached the semifinals or better 52 of the 56 Grand Slams she played, including the semifinals or better of 34 consecutive Grand Slams entered from the 1971
US Open through the 1983
French Open.
[5] Evert never lost in the first or second round of a Grand Slam singles tournament and lost in the third round only twice. In Grand Slam women's singles play, Evert won a record seven championships at the French Open and a co-record six championships at the US Open (tied with
Serena Williams).
Evert's career winning percentage in singles matches of 89.97% (1309–146) is the highest in the history of
Open Era tennis, for men or women. On
clay courts, her career winning percentage in singles matches of 94.55% (382–22) remains a WTA
record."
Evert also won 125 consecutive matches on clay. Lost a final set tiebreak to Austin at the Italian, then won a further 72 consecutively. That's 197 out of 198 matches on clay. You don't have this kind of record if your shots breakdown. They rarely did for Evert. Even on grass at the US Open, Wimbledon or the Australian where she faced a slew of serve/volleyers.