Not quite.
I have consistently supplied the historical data that shows the low success rate of even the top 100 prospects from Baseball America becoming above average major league players.
And of course you saw the Orioles and Athletics as playoff teams last year during the prior offseason??
Heck both those teams might make the playoffs again this year.
I'm going to ignore the rest because we're going around in circles. To the first point, you were saying they could have added Fielder, brought back A-Ram and brought in a pitcher and would have had a good shot at 90 wins. That's the speculation I was referring to. Call WAR a broken metric all you want but that's flat out opinion.
As to the second point, it's interesting you bring both those teams up.
Oakland had Tommy Milone(prospect gotten by trading Gio Gonzo) win 13 games, Jarrod Parker(prospect gotten by trading Trevor Cahill) win 13 games, and Bartolo Colon(cheap FA signing similar to Baker/Maholm/Feldman) win 10 games. Offensively they had Josh Reddick(acquired in a trade for Andrew Bailey) step up and hit 32 HRs. The only FA splashes they made were with Jonny Gomes($1 million, one-year contract), Colon(1 year $2 million deal), Crisp(two year, $14 million deal) and Yoenis Cespedes(4-year, $36 million).
As for the O's, they had Chris Tillman(part of the Bedard trade) win 9 games, Miguel Gonzalez(signed to a minor league deal after flaming out with BOS/LAA) win 9 games, Jason Hammel(traded with Matt Lindstrom for Guthrie) win 8 games, Tommy Hunter(traded with Chris Davis for Koji Uehara) win 7 games, and Wei-Yin Chen(signed as an International FA for three-year contract worth $11.3 million). Offensively, Matt Wieters(home grown prospect) hit 23 HRs, Mark Reynolds(traded for David Hernandez and Kam Mickolio) hit 23 HRs, J.J. Hardy(trade with utility infielder Brendan Harris and $500,000, for minor league pitchers Brett Jacobson and Jim Hoey) hit 22 HRs, Adam Jones(also part of the Bedard trade) hit 32 HRs, and Chris Davis(previously mentioned Uehara trade) hit 33 HRs.
I'm not going to sit here and say the moves Theo and company have made will turn out as well as the moves the O's and A's made because no one can know that. But neither of those 2 teams were built through FA. The biggest splash either of these teams made was the A's signing Cespedes. In fact, both of these teams were built very similarly to what the cubs have been doing the past 2 years. The main difference is these teams are a few years farther down the road with their trades than the cubs are today. Is trading Garza and Dempster really any different than Cahill and Gonzo?
Milone, Parker, Reddick, Jones, Tillman, Davis, Hardy, Hammel, and Reynolds all came in trades. So, here's 2 recent examples of teams coming from no where who have taken a very similar approach to the cubs. They built the team by smart trades and farm system not via expensive FAs. The 5 years prior to last year BAL had 69, 66, 64, 68 and 69 wins. The 5 years prior to last year OAK had 74, 81, 75, 75, 76 wins. The cubs last year years are 61, 71, 75 and are on pace for 74 wins this year. And in all honesty I think the Baltimore comparison is truly a good one. They are a bigger market team who for years spent on FA talent trying to keep up with BOS/NYY and instead focused on their farm system and making smart trades while they tried to rid themselves of bad contracts.
So, while you're welcome to your opinion that the cubs should be spending more in FA, there's a lot of data that points to what they are doing as being a viable plan.