The Focke-Wulf 190 was seen as one of the most effective fighters of the war on either side. In that sense, it was an effective match for the Mustang. However, these two airplanes were not put into direct competition as much as the Mustang and the Messerschmitt 109 were.
The FW-190 was not really designed to be an airplane that could dogfight with quicker planes like the Mustang. It was more of a ground support and multi-purpose fighter. It is also important to note that the FW-190 was an old design and therefore not cutting edge like the Mustang was. In this sense, the FW-190 was not an effective match for the Mustang.
Because the FW-190 was older and less agile, the Luftwaffe tried not to send it against the Mustangs. The tactic they tended to use was to have the Me-109s try to engage the Mustangs while the FW-190s went after the bombers. The Luftwaffe knew that the FW-190 were much better suited to destroying bombers than to dogfighting.
So, the best answer to this is probably that the FW-190 was a very effective fighter but not a match for the Mustang. The two were made at different times and for different purposes.
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