Well, she may play 39 tournaments, but she probably loses in the first and second rounds of every tournament, so she doesn't get that tired because she plays little. That explains her ranking.
Dokic, on the hand, plays 31 tournaments, but either loses early, get to the quarters and semis, or wins it. She is playing probably 30 more matches than this girl.
Dokic better withdraw from some tournaments because I smell a burnout!!
Good Luck: RENA, MATTEK, HAYNES, GULLICKSON, HARKLEROAD, RUBIN, GRANVILLE, LEE-WATERS, SCHNYDER, JACKSON, PERRY, KING, SUGIYAMA, PIERCE, TULYAGANOVA, IVANOVIC, KUZNETSOVA, MOLIK, DANIILIDOU, MEDINA GARRIGUES, PETROVA, PENNETTA, GOLOVIN, PEER, LI, SCHIAVONE, RAZZANO, ZVONAREVA, SPREM, SREBOTNIK, VINCI, & SAFINA