When Van Dorn took the Arkansas troops east of the Mississippi in 1862 he left the state undefended. So almost every soldier that was recruited or drafted in-State, stayed in-State. Meanwhile, the Ark. regiments in the Western Theater went through illness and breakdown and capture and desertion and death and wounds without anyone to replace them. The 30th/25th was in the heaviest fighting at Murphreesboro and lost soldiers heavily. They were continually losing men from the time they signed up at Jacksonport, Ark. through the end of the war. When my Grandpa was elected 3rd Lt. before Chickamauga he was one of 14 men in his company. They just kept consolidating.
By the way, be sure to put Arkansas Confederates in the Western Theater by James Willis on your reading list. The second half of the book is about Reynolds Brigade, including the 25th.