This one can be filed under the same reasoning as Roger McCreary. If you look back on that list of cornerbacks with less than 29″ arms you will see that Marcus Jones is joining McCreary in trying to buck this trend.
Still, McCreary has a few things going that Jones does not. At least McCreary has about 3 inches of height and 16 pounds of weight on Marcus Jones. He also played in the SEC. On top of this, Jones will be a 24-year-old rookie.
Marcus Jones was prolific in the American Athletic Conference, but we know that players can dominate that area of football and never find a chance in the NFL. Jones would not only set a precedent for his arm length, but his height would also be unheard of for a cornerback, as would his weight. Every other successful NFL cornerback to be 5’8″ had longer arms. Every cornerback with his arm length was taller. Every successful cornerback at his weight was longer and taller.
Marcus Jones could find his way in the NFL as a return man. Still, at that point, he is basically in the realm of Tarik Cohen on the defensive side of the field. Even Cohen, who is shorter than Jones was heavier than Jones. It is hard to bet on players this small.
Perhaps if the team needed a slot cornerback who was tough and a return man to be their finishing touch they could draft him. Ryan Poles does not have the luxury to bet on a fun player who historically never works out.