There is a bit more than this to know about McClellan and Grant.I would have to say no.
Grant and McClellan were the only two commanders on the Union side willing to use siege and attrition warfare. McClellan before Richmond, which was called off by the Seven Days, and Grant before the same city and Petersburg, which he was able to hold due to his vast numerical superiority and his deep and thorough construction of earthworks protecting his lines.
McClellan's first involvement with a siege would have been at Vera Cruz in March 1847 -- Winfield Scott in command, McClellan the junior officer on Scott's staff under R. E. Lee, Joe Johnston and P.G.T. Beauregard. But then he was with Scott for the daring campaign of movement and battle that followed, including the storming of Mexico City. Grant experienced all of that as an infantry officer instead of a staff officer, and Grant also had experienced the campaigns of Zachary Taylor in Texas and northern Mexico.
After that, McClellan was one of the observers in the Crimea, including the Siege of Sebastopol. That's the only experience either one had with a siege between the end of the Mexican War and the beginning of the Civil War.
Once the Civil War starts, McClellan has the campaign in WV, followed by little or no action until the 1862 Siege of Yorktown. Then you have the pursuit of the withdrawing Rebels towards Richmond, where it looks like McClellan wanted to start a siege, only to be delayed by Seven Pines and tossed back by Seven Days, then nearly besieged himself. Grant actually ends up with far more experience besieging armies, even though that is not what Grant wants to do.: Ft. Donelson (briefly), kicking his heels at the Siege of Corinth, Vicksburg, breaking a Rebel siege at Chattanooga, then the Richmond-Petersburg siege.
There is a huge difference between them. McClellan actually looks like he wants to wage a siege. Grant tries to avoid them, but uses them to reap the rewards of his campaigns if he can't end them more quickly. Grant's sieges end in the surrender of Rebel armies; McClellan's do not.
Other Union generals used siege warfare, though. Banks took Port Hudson with it. Quincy Gilmore took Fort Pulaski with it. Henry Halleck took Corinth with it and arguably Pope took Island No. 10 with it. Sherman took Atlanta with it. Sieges are simply procedures soldiers use in certain situations. A soldier using a siege is not the same as a soldier using "attrition".