Landing Evans, Lee, or Benjamin could do Stl. wonders as well. None of those guys are as versatile as Watkins, but could be paired nicely with Tavon Austin. Stl. has plenty of options at WR.
something tells me when you start drafting receivers in the top 10 in back to back years that's a good way to set your franchise back. Especially considering you traded up for Austin last year and you oline is in shambles.
They do have an extra first round pick, which is kind of like found money, taking Watkins AND a LT aren't mutually exclusive propositions, and I would make a case the OL isn't in shambles, but I'll return to that point.
If Watkins grades higher than the LTs, than I don't like the idea of a positional reach, that isn't good either. STL took LT bust Jason Smith with a very high first rounder not too long ago. Though I did think Matthews (or Greg Robinson) would be very good selections, but again, there will be LT options with the second first round pick.
Snead came from ATL, where they already had Roddy White, one of the best WRs in the NFL, and paid a HUGE price to land Julio Jones (must be the second biggest trade after RGIII in the past half decade or so?). They had holes on OL, on defense, but they prioritized adding another playmaker to take their offense to the next level. I haven't heard anybody question that move, now that Jones looks like one of the top 3-5 WRs in the game. Many people think DET, even with Calvin Johnson, needs to upgrade the complementary WR (they have tried, spending second rounders on the Boise State WR that unfortunately is out of the league, as well as Broyles, who had his second ACL tear?), and that is the missing piece of the puzzle for the offense. The Rams added Holt when they had Bruce. Vikings added Moss when they had Carter. Colts added Wayne when they had Harrison. If the CLE doesn't draft a QB or the Rams don't beat them to it, they may add Watkins despite having Josh Gordon, the best WR in the league in 2014. The Bucs could add him, despite having Vincent Jackson and just re-signing Mike Williams to an extension. The league is trending in a passing direction. Like Quez noted, Austin* isn't a WR1-type, though he could be more dangerous and a terror with a weapon like Watkins that defenses are forced to account for and game plan around.
People say STL has spent a lot of high picks on WRs in recent years, but I don't think so. Givens was a fourth, Bailey and Pettis (who would likely be gone if they add Watkins) were thirds, Quick was a high second, but he looks like he was severely overdrafted in retrospect, is having a Jerome Simpson kind of career arc, had a disappointing 18 receptions in year two and was passed up by Bailey (who reminds me of Hines Ward and Derrick Mason and should start next year, even if they add Watkins, leap frogging Givens as well). Austin was a high pick, but the only first round WR in fifteen years since Holt. So you could say if they add Watkins, they are making up for lost time. Having Watkins, Bailey, Austin and Cook would put a lot of pressure on defenses. The NFC West is the equivalent of the wood chipper scene in Fargo

, defenses like SEA and SF are ridiculous (not to mention ARI, close to three top five defenses in the division... and if STL, the youngest team in the league and about to get younger if players like Wells and Dahl go, matures and fulfills their potential, they can be a top 10 defense). STL ran at will the first time at home against SEA, but otherwise were throttled by SEA away and both games against SF. When they can't run, they are dead in the water. They need to have a more balanced offense, and Watkins makes everybody better... not only the receiving weapons, but he will even relive pressure on Stacy, a sobering thought for opposing defenses.
Back to the OL, Aaron is right, Jake Long did stabilize the OL. At this point he is probably a better run blocker than in pass protection, but Fisher wants a dominant running team, and that is another way to take pressure off the passing game, and put pass rushers back on their heels. Unfortunately he did have a torn ACL, but his 2014 money is essentially guaranteed, so he isn't going anywhere (2015-2016 could be different?). He won't be winning too many break dancing contests, but OL don't have to cut as hard as RBs and WRs, so maybe that will make for a more favorable prognosis. And again, hopefully they come out of the first round with Watkins AND Robinson/Lewan/Cujo/Erving. So a rookie LT could be Long insurance in the interim, a long term heir apparent, and slide to RT or guard initially. RT Barksdale played very well. He was a blue chip recruit for LSU that could have gone to a lot of schools, and was drafted in the third round by OAK. They made a mistake by letting him go, he could start for a lot of teams (though that said, STL OL positional coach Paul Boudreau seems to have a knack for coaching up these kind of hidden gems, and that has helped with his development). Saffold, who has been hurt a lot and was somewhat of a disappointment at LT and than shunted to RT with the addition of Long, was a revelation on the inside at RG, and that now looks like his most natural pro position. He may leave in free agency, especially if he can command a big contract as a LT, but he has been hurt a lot, so that is a big question mark in my eyes if a team will overpay. Hopefully they can re-sign him even if he tests the market, but rams beat reporter Jim Thomas gave it about a one in three chance? They could also draft a top interior OL like Baylor's Richardson or Stanford's Yankey. The Rams redshirted Outland Trophy winner and high fourth rounder Barret Jones after a foot injury, who played every position on the line for an Alabama team that won multiple championships, and he is viewed as a future starter at center or guard. This doesn't even account for starters Scott Wells (solid center played well this year, but missed like nine games in 2012 and four or so this year, is approaching his mid-thirties and they could recoup something like $4 million in cap money by cutting him... but he could be back?) and Harvey Dahl (also pretty solid, at RG, it was his injury that led to Saffold being moved to RG, also nearing mid-thirties, and could yield four million in cap savings if cut). IF saffold isn't retained, I could see the team bringing back one if not both of the interior OL vets. The weak link on the OL would be LG, where they employed a platoon or rotation (one guard was former first round bust Chris Williams, he wasn't terrible).
Once Stacy was inserted into the starting lineup, and the offense found its identity by committing to the run game, and especially when Saffold moved to RG, the OL was dominant at times (200 yards against SEA, 250+ against CHI), and were close to a top 5 rushing team, i think. So while they probably could be better in pass protection, a powerful running game takes pressure off the passing game, and that is why I would say the OL looks in good shape, is not in shambles, tatters or disarray. Though this presumes Long's knee injury isn't a career-ender (i think he is about 28, like chris long?), it would admittedly help if they can retain Saffold as he gives a lot of flexibility, though it won't be catastrophic or disastrous if they can't, expecially if Barrett Jones is as good as advertised (he actually has a longer reach than Saffold, and could definitely play guard as well as center, he did both in college, as well as LT, i think?)... and of course, they can draft a top five LT, and/or a top three interior OL.
* Austin. Was it a mistake to move up for him? If so, even more reason to take a true WR1-type like Watkins. I do think when surrounded by Watkins, Bailey and Cook he could present a nightmarish matchup problem. If given a do-over, i have to admit, they could have traded DOWN instead of up, scooped up extra pick/s, KEPT THEIR SECOND and used it on stud guard Larry Warford (their target in the trade down with ATL from 1.22 to 1.30 if Ogletree was gone) and STILL landed somebody like Patterson or ex-Tennessee teammate Hunter. But every team could drive themselves crazy with these kinds of do over scenarios (they could have had Alshon Jeffery instead of Quick with the 2012 second, Mike Williams instead of Mardy Gilyard with the 2010 fourth and Desean Jackson instead of Donnie Avery with the 2008 second?). I do think he was horrifically misused at the beginning of the season, and you got a taste of what he could do in the back-to-back IND and CHI games (i think only player besides Gale Sayers and Jim Brown to have four combined 50+ yard TDs in two consecutive games - which could be flukey, or maybe not... he looked like a pocket Barry Sanders in space against Oklahoma with 344 rushing yards and 572 all purpose yards in one of the best collegiate individual performances i've ever seen). If used properly, I think the jury is still very much out, we don't really know how good he can be, and I wouldn't write him off yet. He also had a long ST TD wiped out early by a penalty (STL was much better in the second half of the season), as well as a long receiving TD, and he also had a lot of drops (as did Cook) though seemed to have natural hands at West Virginia, with something like 115 receptions his last season. So he could have significant upside.