Mostly lower cost international free agents.
I was surprised when I looked at rosters of winning teams, there aren't a lot of big money LA players on their rosters for the most part, there's a few teams, but not many.
Quick look at 2012 signings - BA top 20:
Jairo Beras OF - $4.5M, flop, in A+ hitting .228
1. Franklin Barreto 2B - $1.45, AAA with .841 OPS but .404 BABIP, RC+ 117
2. Luis Torrens C - $1.3M, Rule 5 claim, couldn't stay healthy
3. Jose Mujica P - $1M, jumped to AA this year, nothing special so far (4.4K/9 IP)
4. Alexander Palma OF - $800K, .712 OPS in A ball in 2016, yet to play this year
5. Gustavo Cabrera OF - $1.3M injured in 2014, has never recovered
6. Jose Castillo, P - $1.55M, struggling in A+ ball
7. Luiz Gohara P - $800K, didn't do much until 2016, then traded to Atlanta, just promoted to AA
8. Carlos Belen 3B - $1M, struggling in A ball
9. Luis Castro SS - $800K, failed physical
10. Wendell Rijo SS - $575 ($1.1M offer before he blew an ACL), still struggling in A ball
11. Amed Rosario SS - $1.75M, AAA with .912 OPS (Las Vegas) but .398 BABIP, RC+ 138
12. Amaurys Minier, SS - $1.4M, never got past rookie league
13. Richard Urena SS - $725K, struggling in AA
14. David Rodriguez, C - $600K
15. Deivi Grullon, C - $575, in Clearwater
16. Julio de la Cruz, 3b, $700K, never got out of rookie ball
17. Jose Almonte P - $610, pitching well in A+ ball
18. Sergio Alcantara, SS, - $700K, A+ ball, .678 OPS, RC+ 92
19. Frandy de la Rosa 2B - $700K, A ball, .761 OPA, RC+ 117
20. Jose Pujols, OF - $540K
Point is there are only a few legitimate prospects on this list, Rosario is ranked 8th on BA's 2017 top 100 list, Barreto 14th.
Francisco Mejia, 28th on BA's list, and Reynaldo Lopez, 31st, weren't on the top 20 list that year
Another way is to look at the top 100 list and see how many are LA signings:
2. Yoan Moncada (Cuba) $31.5M - 2015
5. Gleyber Torres (2), $1.7M - 2013
8. Amed Rosario (11), $1.75M - 2012
11. Ozzie Albies - $350 - 2013
13. Victor Robles - $225 - 2013
14. Eloy Jimenez (1) - $2.8M - 2013
15. Francis Martres - ??? - 2012
18. Rafael Devers (3) - $1.8M - 2013
20. Vladimir Guerrero (1) - $3.9M - 2015
21. Anderson Espinoza- $1.8M - 2014
24. Manuel Margot - $800K - 2011
26. Yadier Alvarez - Cuba $16M - 2015
28. Francisco Mejia - $350K - 2012
31. Reynaldo Lopez - $17K - 2012
40. Franklin Barreto (1) - $1.45M - 2012
41. Jorge Alfaro - $1.3M - 2010
47. Leody Taveras (3) - $2.1M - 2015
49. Raimel Tapia - $175K - 2010
53. German Marquez - $225K - 2011
54. Franklin Perez (15) - $1M - 2014
67. Ronald Acuna - $100K - 2014
73. Lourdes Gurriel - $22M - Cuba 2016
80. Sixto Sanchez - $35K - 2015 (just noting that AJ Puk is ranked 83rd)
98. Adrian Morejon - $11M - Cuba 2016
What jumps out is bifurcation among LA signings, either they're top international prospects with big bonuses, i.e. top guys who'd be first to second round picks (given their bonuses), or low cost players with bonuses a few hundred K or in a few cases, 5 digit bonuses, but not a lot of guys in between. This suggests the 2nd tier LA players tend to be overrated, and spreading that money around is more efficient. Sign top guys or a lot of guys, but skip the 2nd tier guys.
LA is important, but the draft is more important. Around 70% of the top prospects (more if you exclude overage Cubans) come out of the draft.
And most of the top 20 LA signings flop, a much higher rate than the 1st rd, and even the 2nd round of the draft.
2012 is a one year snapshot, but the big bonus was a flop, the #1 ranked player was a hit, #11, and two guys who were afterthoughts, the other 18 ranked players have yet to make it.
So good scouts and beating the bushes is as valuable as spending lots of money.