Looking at data from all three major states from the Hindi-belt, a few takeaways could be seen from a look at constituency wise trends of the ECI data:
Madhya Pradesh
25: The number of seats won by the BJP where the Congress might have scored had it formed an alliance with the BSP. The number of votes secured by BSP on these seats were more than the margins with which Congress lost. The SP and the independent candidates played spoilsport for Congress on six seats each. On the other hand, independent candidates stymied BJP's chances of win on two seats. The Gondvana Gantantra Party, which otherwise failed to secure a seat, came on second or third spots in eight constituencies, thereby affecting the outcome significantly.
Rajasthan
14: The number of seats won by the BJP where the Congress seemed to have lost because of independent candidates. If the Congress and BSP had gone into the elections with an alliance, the combine could have won nine more seats in Rajasthan. In addition, the BJP lost to Congress on 13 seats where independents secured more votes than the margin of victory. Rashtriya Loktantrik Party (RLP), which won three seats, also affected the outcome on 16 others in the state, emerging second or third in those constituencies.
Chhattisgarh
23: The number of seats where the outcome was affected by the BSP or the Janta Congress. In these constituencies, the number of votes secured by the BSP-JC combine was greater than the winning margin for either the BJP or the Congress candidate.