Bowler Ratings

PatternStTwCr
Oily:X.XX.XX.X
Medium:X.XX.XX.X
Dry:X.XX.XX.X
Sport:X.XX.XX.X

Bowler ratings are from 1 to 10 in order of Stroker (ST), Tweener (TW), Cranker (CR)

Note: Ratings are only available to our premium members.

General Info

Brand:
Name:Theorem Delta
Reviewed:September 2026
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Coverstock Specs
Name:Super Response Hybrid (HK22)
Type:Reactive Hybrid
Box Finish:500 / 1000 / 1500 SiaAir / Factory Compound
Color:Black / Indigo / Blue
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Core Specs
Name:MC2 Asym
Type:Asymmetrical
RG:2.473
Diff:0.046
Int. Diff:0.017

For details on our standard test layouts, please click here.

The Theorem Delta is the fourth ball to enter the Track lineup with the Theorem name. It is the second ball with a hybrid cover in this line, with the original Theorem from 2023 also being a hybrid. The original used Prime Response Hybrid (HK22), while this ball features Super Response Hybrid (HK22). Both balls share the same box finish of 500/1000/1500 SiaAir with Factory Compound. The original Theorem and the Theorem Delta also share the same MC2 Asym weight block. The change in coverstock allowed this ball to provide more length, a sharper move at the breakpoint, and more total hook than the original Theorem. We also saw more total hook and a stronger move at the breakpoint than the Theorem Pearl. In the current Track line, we saw this ball as less angular than the Stealth Mode Hybrid but more angular than the Criterion Inverse. The Theorem Delta was best on our medium oil pattern, but the length it was able to create made it an option on the dry oil pattern as well.

Stroker

Stroker liked the strong change of direction downlane that he saw from the Theorem Delta on the fresh medium oil pattern. It cleared the front of the lane very easily, storing a ton of energy for the breakpoint. The ball made up for his lower rev rate, creating a very strong move at the back end. He could have his angles open in the front, and the ball was strong enough in the last 15 feet to get up to the pocket. He really liked how strong the ball was through the pins, sawing the 10 pin in half shot after shot. The transition was easy for Stroker to get ahead of with this bowling ball. When the ball

Additional Track Theorem Delta Resources

Click here to visit Track's website to read the manufacturer-supplied information on this ball. Also, see below for the manufacturer-produced promotional video for this ball.

Please remember that our reviews are solely based on our own testing and that you may sometimes find differences between our comments and ratings and the manufacturer's claims. Links to these manufacturer resources are provided here strictly for convenience purposes.

The BTM Ball Testing Team

About The BTM Ball Testing Team

Bowling This Month's ball testing team is led by Eric Martinez. Our team of three testers has reviewed well over 1,000 bowling balls for Bowling This Month. In addition to leading BTM's ball testing efforts, Eric owns and operates University Pro Shop in San Antonio, TX, and he is an avid competitive bowler. Learn more about our bowling ball testing and review process here.