Matching a turbocharger compressor and a turbine seeks to balance the turbine characteristics to the compressor characteristics. Compressor Turbine mismatch causes poor engine performance.
Increasing the size of the turbine wheel decreases the pressure ratio of the turbine which decreases the compressor/turbine shaft speed. When pairing a large turbine wheel to a small compressor wheel, the compressor wheel RPM must be increased to compress the inlet air. The problem this creates is that the smaller compressor cannot generate adequate shaft speed at low engine RPM to compress air.
When pairing a small turbine wheel with a large compressor the larger compressor requires less shaft speed to compress airflow resulting in less turbo lag. But the smaller turbine wheel can reach its rpm limit and cause excessive exhaust back-pressure. The result is turbo damage and lower maximum power than possible with larger turbine.