Answer
The mass of a baseball is so large that the uncertainty principle barely matters, while the mass of an electron is incredibly small.
Work Step by Step
The uncertainty principle is defined as $\Delta p \Delta x \geq \frac{\hbar}{2}$, or $\Delta v \Delta x \geq \frac{\hbar}{2m}$, if $p$ is replaced by $m\Delta v$. This equation shows that as mass increases, the precision increases. So, for a small object like an electron, there is a high amount of uncertainty, but there isn't much uncertainty for a large object, such as a baseball.
