Checked to verify: "What's in Patrick Cantlay's Titleist Golf Bag" and found fourteen clubs. My findings, with respect. What was the additional club you found?

TS3 (10.5°) driver w/Mitsubishi Diamana BF60 TX
915F (15.0°) fairway metal w/Diamana ZF70 TX
816H2 (21.0°) hybrid w/Fujikura Atmos 8 Blue X

718 AP2 (4-9) w/TT Dynamic Gold 120 X100 (six irons)

Vokey Design wedges w/TT Dynamic Gold S300 (four wedges)
SM7 pitching (46), gap (54.10S), sand (56.08M)
SM8 lob (61°)

Scotty Cameron GSS putter

Pretty sure if he had 15 clubs in the bag he would have been told

Tour golfers typically travel with more than 14 clubs, swapping out fairway wood for hybrid or different wedges in order to best match the conditions of the course each week. And, that doesn't count the 'back up' pieces that would stay in the trunk unless needed.