The shift towards a more sustainable energy supply has multiple unprecedented impacts on the European electricity infrastructure. Recently launched energy data hubs and data platforms offer large datasets that can allow for detailed quantitative assessments. The advanced tools of data analytics can make an essential contribution to highlight the multifaceted implications of the energy transition. As a research objective, the paper addresses the altered role and operating conditions of thermal power plants using fossil fuels. The applied methodology relies on a structured data cleaning and technology-specific preprocessing of hourly generation output data of 810 large thermal units located in 19 European countries, covering the period 2016-2024. As thermal power plants are increasingly seen as sources of flexibility, the analysis focused on operational and cycling characteristics. The set of indicators related to utilization and operational flexibility covers capacity factors, load factors, running hours and total startups for hard-coal fired, brown coal/lignite-fired, oil-fired and gasfired units. Unlike studies relying on aggregate country-level statistics, limited to a high-level analysis, the methodology based on unit-level time series provides quantitative empirical evidence on the main implications of the energy transition on the operation of thermal power plants.