I. West Bengal
The seats won and vote shares (in %age) polled by the parties (2019/2014):
TMC: 22 / 34 (-12) and 43.28 / 39.05 (+4.23)
BJP: 18 / 2 (+16) and 40.25 / 17.02 (+23.23)
INC: 2 / 4 (-2) and 5.61 / 9.58 (-3.97)
CPI(M): 0 / 2 (-2) and 6.28 / 22.96* (-16.68)
L.F.: 0 / 2 (-2) and 7.46 / 29.71 (-22.25)
(Including and led by CPI(M))
(Ref.: <
http://results.eci.gov.in/pc/en/partywise/partywiseresult-S25.htm?st=S25>
and <
https://en.wikipedia.org/wiki/2014_Indian_general_election_in_West_Bengal>.
* - Source: <
https://indianexpress.com/article/india/lok-sabha-election-results-lefts-worst-show-zero-in-west-bengal-five-in-all-5745572/?fbclid=IwAR0mwmtrgX-55sUXsXSby3-rMOlRe0YQO9WVlYF4uubzToeUAjjwdCwT0QM>.)
So, the seats aside, the TMC has added (rather modestly) to its (already fairly high) vote share - 4.23% points.
The BJP has seen a quantum jump - it has more than doubled, added 23.23% points.
Only 3.03% points shy of the TMC.
That's what explains the vertical leap in the number of seats from 2 to 18.
Wherefrom these additional votes (27.46%) came???
The Congress lost 3.97% points and the Left Front - 22.25% points.
Both together: 26.22% points.
(Also look up: <
https://indianexpress.com/article/india/lok-sabha-election-results-lefts-worst-show-zero-in-west-bengal-five-in-all-5745572/?fbclid=IwAR1DsKgsX80ZKx17RvMr0cjOZZZuaAxqdzViBUjMYyzZz_ufJy2Nf3ot2pM>, <
https://www.thequint.com/voices/opinion/bengal-bjp-trinamool-modi-mamata-saffronisation-2019-lok-sabha-elections?fbclid=IwAR11l8FNBJ0_VuhQylNxNcR_Gk3RvdWbfKIVBCj23qz2ynTrDTYnU1I6yZA>, <
https://thewire.in/politics/west-bengal-elections-bjp-mamata-banerjee?fbclid=IwAR0En43v08BgetddZ8ag3OBz-bgUfxHTzDzKxMQJUClDUPXcNRA8uXo0z6g> and <
https://www.asianage.com/opinion/oped/240519/saffron-tide-overtakes-bengal.html?fbclid=IwAR3VchipfPwTRoOcrqEwgvaaV57gcB5IrZ6EyqNNHnzcVUXqXu5Sh0QcKTU>.)
II. Kerala
INC: 15 / 8 (+7) and 37.27 / 31.10 (+6.17)
BJP: 0 / 0 (0) and 12.93 / 10.33 (+2.60)
CPI(M): 1 / 5 (-4) and 25.83 / 21.59 (+4.24)
Last time, the CPI(M) had 10 candidates, whereas this time it had 14.
The remaining seats were contested by other LDF candidates.)
So, last time, each CPI(M) candidate had polled, on an average 2.159% of the total votes polled statewide. This time, it is 1.845.
Thus there's a fall in vote share per candidate.
(Ref.: <
http://results.eci.gov.in/pc/en/partywise/partywiseresult-S11.htm?st=S11> and <
https://en.wikipedia.org/wiki/2014_Indian_general_election_in_Kerala>.)
That, apparently, explains how the INC and the BJP, both, have raised their vote shares this time.
There's, obviously, a net outflow of votes from the LDF - mostly, to the UDF and a smaller fraction to the BJP-led front, as it appears.
III. Delhi
BJP: 7 / 7 (0) and 56.56 / 46.40 (+10.16)
AAP: 0 /0 (0) and 18.11 / 32.90 (-14.79)
INC: 0 / 0 (0) and 22.51 / 15.10 (+7.41)
(Ref.: <
http://results.eci.gov.in/pc/en/partywise/partywiseresult-U05.htm?st=U05> and <
https://en.wikipedia.org/wiki/2014_Indian_general_election_in_Delhi>.)
Also relevant:
"In Delhi, all the seven Bharatiya Janata Party candidates secured more than 50% vote share in the Lok Sabha elections, the results of which were declared on Thursday. The Aam Aadmi Party was set to finish runners-up in two (out of seven) seats."
(Ref.:<
https://scroll.in/latest/924499/2019-election-results-bjp-secures-more-than-50-votes-in-all-seven-seats-in-delhi?fbclid=IwAR3w6hb9drNTHGZjgY6MPqsUqA0htxiLJ3fLMPVxGpk3lBCn1Xv85HXKRYI>.)