Link adaptation is the technique through which eNodeB changes MCS coding schemes when channel condition at air interface varies. Suppose channel condition is bad then eNodeB selects lower MCS coding scheme and when channel condition is good then it selects good MCS coding schemes for UL/DL data transmission.
Suppose link adaptation is used at eNodeB. In that case eNodeB shall use fixed MCS coding scheme and will not vary when channel condition is changing. So If channel condition getting bad in that case eNodeB will not change the MCS coding scheme for data transmission. Due to bad channel condition receiver can not receive data as eNodeB is not selecting suitable MCS coding scheme. This will increase the data re transmission will decrease the throughput of the enodeB.