Deciding on a method for distributing customer service queries depends on an analysis of the tickets to understand how much variation there is the complexity of the queries and analysis of the agents to understand the variation in their ability.

This analysis isn’t to understand how complex the queries are, but to understand how different the queries are. If some of the queries are simple and some very complex, this is a high variation in complexity, and if all the queries are simple or all complex then this is low variation in the complexity. If the analysis of the difference in agents ability shows that some agents have lots of knowledge and ability whilst others have very low level of knowledge and ability then that is a high variation, but if all the agents are equally knowledgeable then the variation is low.
Assigning customer service agents

High variation in the complexity of queries and high variation in the abilities of agents

If there is a high degree of variation in the complexity of the queries, meaning some can be resolved easily in a few seconds whilst others take days or even weeks to reach resolution, and if the variation in the ability of the agents is high, due to some agents having lots of experience and others having a lower level of knowledge, then distributing tickets across the team using a load balancing method is best. This means that agents with more ability can be assigned and resolve more tickets than agents with lower ability who will be slower.

High variation in the complexity of queries and low with variation in the abilities of agents

If the queries the team receive have a high variation of complexity but there is a low variation in the abilities of the agents as they all have similar levels of knowledge and experience, then manually triaging tickets can often be the most efficient method of assignment. The second most efficient method would be load balancing as complex tickets will take longer to be resolved by a one low ability agent as much as any other low ability agent.

Low variation in the complexity of queries and high variation in the abilities of agents

If the majority of the queries are of a similar complexity (high complexity or low complexity) and there is a high variation in the abilities of the agents, because some are new to the role whilst others have more experience for example, then using a Skills based approach to assign tickets is an effective option. Agents with particular knowledge will be assigned tickets that require their expertise whilst agents with less experience will be assigned the tickets that only require more general skills.

Low variation in the complexity of queries and low variation in the abilities of agents

If the type of queries the team receive are mostly of a similar complexity, e.g. all about similar topics and the abilities of the agents are all approximately the same, which means they all resolve tickets at a similar rate, then using round robin to distribute tickets equally across the team is the most efficient method.