The phrase "a relevant player" is correct and usable in written English.
It can be used to refer to an individual or entity that has significance or importance in a particular context or situation.
Example: "In the discussion about climate change, the government is a relevant player in shaping policy and regulations."
Alternatives: "an important participant" or "a significant contributor".
After entering the union in 1995, the country has become a relevant player in European politics, much more so than our size would suggest.
"There's plenty of them to explain about how they're going to remain a relevant player in the smartphone market," said Nick Dillon, an analyst with Ovum in London.
"Santorum's personal popularity is the main reason for his sudden re-emergence as a relevant player in the G.O.P. race," Tom Jensen, a Democratic pollster and director of Public Policy Polling, wrote in an analysis of Tuesday's votes.
Google became a relevant player in social networking this year with the successful launch of Google+.
The reduction on the installation costs for PV systems has converted this technology into a relevant player regarding the electricity matrix.
Glycogen synthase kinase 3β (GSK-3β) is widely recognised as a relevant player in the pathogenesis of several highly prevalent disorders such as Alzheimer's disease, mood disorders, diabetes and cancer.
Hi5 has recently laid off a good portion of its staff but continues to be a very relevant player in the social networking field; it is still the third largest social network after Facebook and MySpace according to Comscore.
Thus, TIS-T lymphocyte emerges as a new relevant player in the complex interaction between tumor and tumor-infiltrating cells that influences tumor progression.
Altogether, these findings suggest that Gal-3 is a biologically relevant player for neuroblastic tumors, whose determination by conventional immunohistochemistry might be used for outcome assessment and patient's risk stratification in the clinical setting.
In order to verify that Grb14 is a potentially biologically relevant player in the Tie2 signaling pathway, we examined for the presence of Grb14 in a number of endothelial cell lines.
"Board members began establishing the details of the allegations, speaking to all relevant players and staff.
