DEL MAR, Calif. - Handicappers who appreciate track bias have always had a soft spot for Del Mar. When the summer bias showed up, it was blatant, and easily exploited.\nSome attributed the inside speed bias to ocean tides. The theory was never corroborated, but what the heck? Fact and fiction are intertwined at the racetrack.\nThen came the great Del Mar flood in winter of 1980, after which the main track at Del Mar became a haven for rally-wide closers. They would circle the field on the turn, sweep to the lead in deep stretch, and pull away. As for inside speed, it was all but dead.\nIn the 1990s, contemporary maintenance procedures changed Del Mar. It became Santa Anita, farther south. Both surfaces favored speed, and though the bias was not always obvious, a handicapper could generally begin by finding the speed and going from there.\nThen along came synthetic racing surfaces. And once again, handicappers are forced to reexamine the influence of surface on the dynamics of a race. This summer at Del Mar the shift has been extreme. Not that it should be a surprise.\nEveryone knows the surface at Hollywood Park - they still call it Cushion Track, although it behaves like dirt - is the only major Southern California racetrack where early speed is an asset. From late April to late July, front-runners generally rule the circuit.\nWhen the 2009 Del Mar meet opened July 22, many handicappers expected Polytrack to produce increased positional movement. Here come the closers. Polytrack tends to be slower than Cushion Track, and late-runners who spun their wheels at Hollywood would have a greater chance at Del Mar.\nSix days into the meet, horseplayers have discovered that from one card to the next, no two surfaces are alike at Del Mar. While it is true the main track generally is slow, it is not slow always. While it is true that late-runners win more often on a slow track, sometimes the exact opposite is true. And the shifting nuance of Polytrack is testing the patience of bettors.\nThe main track was slightly slow opening day, July 22, although not by much. The older maiden Zavata earned a Beyer Speed Figure of 84 after running six furlongs in 1:11. The final time and resulting figure were reasonable. No problem.\nOnly two days later, the speed of the track had changed radically and was quicker by approximately four-fifths of a second. Hockeythehayman ran six furlongs in 1:10.26 to win a maiden-40 starter on Friday. If the track had been the same speed as it was two days earlier, he would have run 1:11 or slower, similar to the maiden special weight.\nAs a standalone factor, track speed is not normally a major concern. A prime utility of Beyer Speed Figures is they incorporate track variant (track speed) into the figure, which allows handicappers to compare horses who ran on different surfaces, race days, or different distances.\nThe challenge for handicappers this summer at Del Mar is the shifting speed of the main track and its profound influence on the bias. This is not a major revelation. On a fast surface, speed often carries. On a slower and tiring surface, the speed often backs up.\nThe problem is to fashion a reasonable analysis without knowledge of how fast or slow the surface will be.\nAnyone who predicted the July 25-26 surface would be wickedly fast might have made a mint. The surface on Saturday, July 25, was fast and favorable to speed. Million Dollar Run had not raced in 10 months, yet won despite racing only two lengths behind the meet's fastest opening quarter (22.02 seconds).\nEvery sprint winner July 25 raced on or near the front. The speed bias particularly compromised the race 4 odds-on favorite, Lethal Heat, and race-6 favorite Saucey Evening.\nAnother fast surface on Sunday, July 26, propelled 3-year-old claimer Quiet Lightning to victory in race 3, despite an opening half in 44.79 seconds. A $12,500 claimer, Quiet Lightning is the only six-furlong horse (through 16 races at the distance) to get the first half of a six-furlong race in less than 45 seconds. And he kept keep going.\nThe first week of the Del Mar meet is always a learning curve, and perhaps handicappers could have expected that when racing resumed Wednesday for week 2 that the main track would be slower. Del Mar renovated the surface during the Monday-Tuesday dark days.\nFew expected the surface would be the grueling bog that produced the slowest times of the meet and compromised the chances of every speed horse. The first race Wednesday was a $50,000 maiden claimer for fillies and mares that would normally be clocked in about 1:11.60. It went in 1:12.25.\nDel Mar brought out the water truck after race 1. It did not matter. Race after race, final times were laborious. Closers dominated. The Graduation Stakes for 2-year-olds was timed in a slow 1:05.15 for 5 1/2 furlongs as late-runners ran amok on the longshot-filled card.\nBy race 6 on Wednesday, the bias was so conspicuous many riders were reluctant to let their horses use any speed.\nSo when jockey Michael Baze put Dixie Unioness on the front in race 6, a one-mile race for maiden fillies and mares, no one took him seriously. Dixie Unioness lollygagged the opening half-mile in 49.18 seconds and six furlongs in 1:14.07.\nShe wired the field at $63.40.\nIt's still early in the meet, but currently things are upside down at Del Mar.\nIt is so weird that an anti-speed bias Wednesday was the main reason longshot front-runner Dixie Unioness was able wire the field.