Horsemen are increasingly vocal regarding the “deep, tiring” main track at Del Mar (Daily Racing Form: http://bit.ly/2vSXWlU). Meanwhile, handicappers are learning to adjust.

Most main-track winners are forwardly placed, particularly around two turns. However, horses do not win because they have speed. Rather, they have speed because they handle the surface. The formula: handle the surface, produce speed, win the race.

Other horses are uncomfortable with the footing. They drop to the rear, and stay there.

Handicapping can be tricky. It is even trickier over the slow, tiring Del Mar surface so many horses are struggling with this summer. The challenge is to identify the horses that will handle the going, and the horses that will not. Thursday preview …

Race 1 – Oh Newman (1) might not stay two turns, but he does have a good recent race over the Del Mar track. His third last out in a sprint was over a slow surface, so he does like the track. Staying one mile will be tough. Oh Newman is a must-use; top choice is Tiz Jolie (3).

Race 2 – Pacesetters are 4 for 14 in turf routes at a mile and a sixteenth. At every other turf route distance, pacesetters are a combined 2 for 28. But good luck to the speed in this mile and a sixteenth claiming turf race. Three of the six entered are front-runners; the race sets up for Warm Endowment (1) and Comet Sixty Two (2).

Race 3 – Clifton Beach (11) made the DRF “Horses to Watch” list after a troubled fourth last out. He is second preference in this maiden-20 sprint; top choice is dropper Rafter One (8). Have to use both.

Race 4 – First-time starter Angel Allie (3) has two unrecorded works according to National Turf clocker Andy Harrington. The filly worked “at least” three furlongs on Aug. 5 and a half-mile from the gate on July 23. Neither work was recorded. First-time starter Cool Munnings (1) is this handicapper’s top choice, both firsters must be used.

Race 5 – The Street Fighter (9) has worked super for his comeback. Those workouts, obviously, are in the morning. The Del Mar main track often changes from morning to afternoon. The Street Fighter can win this Cal-bred allowance if he handles the surface in the afternoon.

And that is the main handicapping challenge of summer: trying to identify the horses that will handle the going, and the horses that will not. First post Thursday is 2 p.m.