The power rankings rate members of Congress based on position by virtue of committee or tenure, indirect influence through media influence or caucus membership, the number of bills or amendments that each member succeeds in getting passed and how successful they are at getting earmarks for their state or district.The site does say that there are limitations to the rankings:
The Knowlegis Power Rankings project team acknowledges that Members of Congress sometimes exercise power in ways that cannot be seen or measured. For example, we did not measure some variables such as effectiveness in assisting constituents in the district and state, known as "casework." Nor did we measure legislators' visibility in the district and state, such as public appearances or communication with voters. Finally, legislators often play important roles as liaisons with federal agencies in matters where state or local governments have a vested interest in a special project (such as military base closures). These factors - while crucial to a member's re-election and extremely important to constituents - are hard to measure and rarely contribute to power in the House or Senate.Factoring in these limitations can only drop Kline further. Visibility in the district and state? We are represented by a man who has virtually no influence and who uses what little influence he has to vote against the interests of his constituents.