The Imperial Russian Army was corrupt as heck, morale was very low and they were both worn down and war weary by 1917 - having basically been at constant war since *1904*. The Army being on the monarchists’ side was far less of a benefit than it would sound.
Interesting point - I was basing my statement on the performance of the White Army and that Trotsky managed to co-opt some of the Tsarist army into the Red army