It can contribute to numbing. That's why people who use it tend rub it on their gums--it causes an immediate, pleasant, lasting numbing sensation. Standard use tends to dull pains/aches throughout the body as well, though to a somewhat lesser degree than direct local contact/absorption. And yes, it also can give you quite a bit of excess energy (and thus potential output) which obviously scales with dosage. The crash can be pretty hard though if you use a lot at a time, but this can be mitigated by consistent dosing.
The thing about cocaine is it doesn't stay in your system for that long--a couple of days, typically. So if he tested positive, he would have been using rather recently. It's not like cannabis where it can stay in your system for up to a month (or even longer in some cases) after a single use.
The real magic is with the combined effects working together--the dulling of pain and the excess energy boost. Normally, when you push yourself really hard in a short span of time, you will start to 'feel the burn' or ache, etc; you have your limits, basically. But with cocaine, due to the interaction of its effects, generally you'll be able to not only push harder for longer due to excess energy, but also you aren't as susceptible to your normal 'limits' because that 'burn' is no longer a significant factor. You'll feel it the next day of course, and there are certain things that no amount of cocaine will prevent obviously, but while you're still high, you're generally not going to be getting very exhausted or depleted.
In fact, a lot of times you'll have so much energy as a result of your high, that you'll be compelled to expend as much of it as possible. There's this "bottled up" sensation, similar to an adrenaline rush. This is part of why cocaine and aggression often go hand in hand, because all that energy needs an outlet, and aggression is generally a good outlet for it.
Cocaine is a fairly addictive substance. The more you use, the more you tend to want, and the more you use, the higher your tolerance becomes, which means you incrementally increase your dosage over time. It's highly unlikely this was a one time thing for Jones. It's an expensive addiction to have, but Jones has the income to support it. So it wouldn't be surprising to know that it was habitual.