The phrase "underwhelming performance" means that something or someone did not meet the expectations or was not as impressive as expected. Full definition
After a slew of underwhelming performances early in the season, he saw his starting spot disappear. (serpentsofmadonnina.com)
Permanent Secretary / Secretary to the Police Commission, Mr. Musa Istifanus disclosed this on Monday, October, 9th, 2017, while receiving the leadership of the «Concerned citizens of Edo State» who were in the Commission to protest against what they called the continued underwhelming performance of the Commissioner of Police in the State, Mr. Haliru Gwandu. (securitykingng.org)
Despite its own underwhelming performance at the local elections, Labour was buoyed as a new poll by Tory peer Lord Ashcroft showed that Ed Miliband's party was 12 % ahead of the Tories in 26 key marginal battlegrounds. (theguardian.com)