Problem 1609

1. We need to find the smallest even number of teams such that each team has exactly 9 people and the total number of people is at least 38.
2. Let $n$ be the number of teams. Since each team has 9 people, the total number of people is $9n$.
3. We need $9n \geq 38$ and $n$ must be even.

4. First, solve for $n$ in the inequality $9n \geq 38$:
$$n \geq \frac{38}{9} \approx 4.22$$
Since $n$ must be an integer, the smallest integer $n$ that satisfies this inequality is $n = 5$.

5. However, $n$ must also be even. The smallest even integer greater than or equal to 4.22 is $n = 6$.

6. If $n = 6$, then the total number of people is:
$$9 \times 6 = 54$$

7. The number of additional people needed to reach 54 from 38 is:
$$54 - 38 = 16$$

Conclusion:
The fewest number of people who must join the CBL such that the CBL can start playing games is $\boxed{16}$.