Was the Piazza Trade Underrated?
This one will be a bit numbers heavy. I'm not pulling any of these numbers out of my backside - any projections are legitimately based on the numbers. That being said, all the attempts at quantifying defense are just fudges, and I chose to round out a lot of stuff for simplicity's sake (and uncertainty's sake). This is intended as an illustration, not a study.
Forget about what happened after the Dodgers-Marlins' 1998 trade, for the time being. Just look at the available info at the time of the decision. Piazza looked like an obvious future hall of famer, no doubt. He was a catcher coming off of an almost unparalleled two-year stretch of offensive brilliance. That being said, there can also be no doubt that he had already peaked. The Dodgers attempted to sign him to a long-term deal. I've got no clue what the finances involved were, but for whatever reason, the Dodgers and Piazza hadn't come very close to an agreement. This made Piazza a free agent at the end of the season. So they swapped him and a veteran 3B for a star signed long-term, a slightly better veteran 3B, a rising star at catcher, a salary dump throw-in, and a pretty good relief prospect. When you trade one year of a player for a gaggle of good players, you generally have to screw up the finances to come out worse for it.
What could LA have expected in terms of net gain? Piazza was a historically great offensive catcher, but on the flip side was a lousy defensive catcher. I'm just going to use quick and dirty numbers here, so let's say that his defense is bad enough that it essentially cancels out. A reasonable offensive projection for him at the time tops out at 5.5 wins above average or so, so lets call him 7.5 wins above replacement. The Dodgers would be replacing him with Charles Johnson, who had been an average hitter so far in his career with outstanding defense. A conservative projection for Johnson would be about 3 wins above replacement. At third base, the Dodgers would replace Todd Zeile with Bobby Bonilla. Both were mediocre fielders, and Bonilla had been a very good hitter his entire career but was two years older. Zeile was coming off of a good season, but a reasonable projection would put Bonilla at about 2.5 wins above replacement with Zeile at +2. Eisenreich was a good hitter, but he was old enough that the Dodgers couldn't expect him to be much better than their bench guys (Luke, Hubbard, etc.), so let's say he has no net effect. Finally, Sheffield takes over for the junk the Dodgers were playing in the outfield beyond Hollandsworth and Mondesi; the best of these players was, I guess, Roger Cedeno. Sheffield would project as about 4 wins above average as a hitter, whereas Cedeno would be about -1. Even if it had been reasonable for the Dodgers to like Cedeno's fielding at that point (it probably wouldn't have been), he's not going to make up much more than 1 win that way. So the Dodgers get +4 in the OF, +.5 in the IF, and - 4.5 at Catcher. Looks pretty even on the field for 1998.
Looking at the player salaries, the Dodgers lose out in '98 because Sheffield had already been signed to a front-loaded extension while Piazza was in his final arbitration year. However, looking at it longer term, Sheffield was signed cheaper for the rest of his deal than Piazza would be earning. So if we consider the haul that the Dodgers were taking in, then the Dodgers give up one $8m year of Piazza and two $3.2m years from Zeile for three arbitration years of Johnson, one $1.4m year of Eisenreich, two $5.9m years from Bonilla, and 6 years of Sheffield at $11m per. For the $14.4m they were taking off the books, the Dodgers could have expected about 11 wins above replacement. In return, they'd be paying a combined $82.5m guaranteed plus about $9m for Charles Johnson's remaining arbitration years. So if we allocate 3 WAR/year to Johnson, 4.5 total for Bonilla's two seasons, and an average of 4 WAR over the life of Sheffield's deal, we get 38 wins above replacement for $91.5m. That's a essentially an extra $77m to get just 27 wins. Let's subtract the cost of replacement salaries and add in about 2 wins of net value from Barrios, who looked like a pretty good prospect at the time. That's 29 marginal wins at $75m, but we need to adjust for inflation; if we assume a constant 10% salary inflation rate, we can take $13m off of that. So in 1998 dollars, the Dodgers would be adding 29 wins at $62m, or $2.1m per win. That was a decent number, but not very good. Using the rule of 70, that would be $4.3m per win in 2005, for comparison's sake, so it's fair to say the Dodgers couldn't expect a great return.
However, the assumption above is that Sheffield was a star, but not particularly good. But let's say his 1997 performance should have been adjusted for injury, and let's not lay on the decline so thick as I did. Moreover, that 3 WAR for Johnson is pretty conservative. Between the two, it'd be fair to add another 6 wins to the projection above, netting a rate of about $1.75m per win. There's no way that this can be spun as a great deal. But it's obvious that the FOX-run Dodgers had set the value of a marginal win at much higher than that at the time. So it's certainly defensible.
But if they were willing to spend so much, why not just re-sign Piazza? The Mets inked Piazza for 7 years at $91m, or $61m in 1998 dollars. An optimistic projection at the time would peg Piazza at about 37 wins above replacement over that period. In other words, Piazza would be paid at about $1.6m per marginal win. So, it's fair to say that LA could have had Piazza at the same rate they would be playing his replacements, assuming he would have agreed to what the Mets paid him to stay in LA. Perhaps there would also have been a "hometown discount", but I doubt it would be too substantial.
Then again, Piazza was a heavily worked catcher who wasn't particularly athletic. It wouldn't have been unreasonable to figure that he'd decline at a quicker rate. If he were to merely average an all-star level of 4 WAR per year, a reasonable if unsympathetic projection for seven years of catching, he'd be at $2.1m per year. It's not hard to understand the rationale of the Dodgers; or, rather, it wouldn't be hard if this had been their rationale.
As it turned out, Sheffield was the better bet. In 1998 dollars, he earned $53.5m over the length of his contract while being good for about 32 wins above replacement. From 1998-2005, Piazza earned an adjusted $68.9m for about 36 WAR. Sheffield was paid about $220,000 fewer per win (or half a mil per win on today's market). Adjusted for inflation, Sheffield was paid a little more per year, but he was around .8 wins per year better.
Then again, though Sheffield turned out well and the Dodgers' later trade of him went well, the Dodgers ended up on the short end of the rest of these sticks. While Zeile did a bit better than would have been expected, Bonilla hit a wall; after having been considerably above average his entire career, Bonilla was below replacement level for the entirety of his post-trade career. Eisenreich performed awfully as a Dodger and his career was over. Barrios fell apart.
Most painfully to the Dodgers, Charles Johnson had a terrible year in LA. The Dodgers traded him, and he rebounded with an average season in Baltimore before tearing the cover off the ball in 2000. Since Johnson's performance after getting a big deal in free agency was so mediocre, it's often overlooked that in his arbitration years combined - the period the Dodgers acquired in the Piazza deal - Johnson was an above average hitter and still a good defender, although his numbers behind the plate were way down from his earlier Marlin dominance. The Dodgers received Todd Hundley for Johnson, but they had to give up Roger Cedeno's "peak" to do so and Hundley was making more money than Johnson. Hundley himself had a good 2000, but he was a bad defensive catcher and missed a lot of time to injury; on the whole, the Dodgers would have been a lot better off had they not traded Johnson.
All in all, I don't think the Dodgers made that bad of a deal. However, judged in context, it should be considered a lot worse because of opportunity cost. Dealing with the Marlins in the midst of a fire-sale should have yielded a much better return. Had they made a similar deal with another team, it would look better; as it happened, they ostensibly could have acquired a lot more value. On the flip side, though, the price the Mets paid for Piazza tends to be understated; they traded two pitchers with first-round talent and a pretty good young outfielder Preston Wilson), none of whom had clocked any service time; had Piazza suffered an extra injury here or there (or had the Mets been unable to re-sign him) and Ed Yarnall or Geoff Goetz developed into aces, history would have viewed that trade quite differently. While the Mets were obviously the victors along this trade route, and while the Dodgers likely acted rashly in order to spite Piazza, none of the sides of the Piazza trades were the slam dunks they're often thought to be.